germanium silicon fractionation in the weathering environment abstract we present a detailed study of germanium behavior in the soil weathering environment as an important step toward using the ge si system as a tracer of silicate weathering processes in both modern and ancient environments intensely weathered soils developed on hawaiian basalts have bulk soil ge si ratios 2 to 10 times higher than fresh basalt e g 10 to 25 mol mol vs 2 5 mol mol soil ge concentrations increase with si and decrease with fe suggesting that ge sequestration is related to accumulation of secondary soil silicates rather than retention in soil fe oxy hydroxides sequential extractions of these soils suggest that ge si fractionation takes place by ge sequestration during the initial precipitation of secondary soil aluminosilicates principally allophane further si loss and changes in mineralogy as these soils age result in little additional ge si fractionation ge si ratios in granitic soils and saprolites are strongly influenced by relative weathering rates of primary minerals kaolinite has a ge si ratio 5 9 mol mol higher than the plagioclase from which it forms 3 1 mol mol whereas accumulation of primary quartz ge si 0 5 mol mol prevents granitic soils from attaining high ge si ratios laboratory synthesis of allophane confirms that ge is preferentially partitioned into the solid phase upon precipitation of secondary aluminosilicates from solution

chronology and petrogenesis of a 1 8 g lunar granitic clast 14321 1062 abstract a study was undertaken to determine the chronology of a pristine granite clast 1062 from apollo 14 breccia 14321 using rb sr sm nd and 39ar 40ar methods the genesis of the granite as constrained by the isotopic results and trace element characteristics is discussed chronology the rb sr internal isochron is slightly disturbed and yields an age of 4 09 0 11 ae 87 rb 0 0139 ae 1 and an imprecise initial i sr 0 702 008 if two data are excluded the age becomes 4 13 0 03 ae and i sr 0 698 003 the whole rock and mineral separates are extremely radiogenic they yield model ages which are relatively well defined the average model age is 4 12 0 03 ae relative to babi 0 69898 the sm nd internal isochron is also slightly disturbed and gives an age of 4 11 0 20 ae 147 sm 0 00654 ae 1 the 39ar 40ar average age of the non magnetic fraction of the sample yields a slightly younger age of 3 88 0 03 ae k ar constants from steiger and a 1977 the concordancy of rb sr and sm nd internal isochrons with the rb sr model age strongly suggests that the granitic clast formed at 4 1 ae ago in the shallow crust and was later excavated and brecciated about 3 88 ae ago petrogenesis isotopic and trace element data of the lunar granite show large k la and rb sr fractionations small sm nd fractionation and the distinct v shaped ree distribution pattern at the time of crystallization a two stage model involving crystal fractionation followed by silicate liquid immiscibility sli is proposed for lunar granite genesis we propose that the granite can be the immiscible acidic liquid produced by sli from a residual liquid which underwent fractionation of ca 3 of phases with ree distribution coefficients similar to those of phosphate minerals from a highly evolved parental magma with ree contents about twice those of the 15405 85 quartz monzodiorite qmd the extreme scarcity of lunar granitic samples and their young formation ages suggest that they are probably not directly crystallized from the differentiation of the primordial magma ocean our isotopic results and trace elements data from other workers suggest that granites qmd and probably mggabbronorites may be genetically related and may have formed in a plutonic environment similar to gabbro granophyre associations in terrestrial layered intrusions such as the skaergaard intrusions

silicic volcanism at ljosufjoll iceland insights into evolution and eruptive history from ar ar dating abstract ljosufjoll volcano is the largest outcrop of silicic volcanic material in the volcanic snaefellsnes flank non rifting zone of iceland the silicic eruptives range from trachytes to alkaline and peralkaline comenditic rhyolites and show evidence for eruption in both subaerial and subglacial environments thirteen silicic eruptive units have been identified and mapped by a combination of field observations and geochemical correlation the trachytes probably formed by fractional crystallisation of a basaltic magma to form an alkali feldspar rich trachytic mush with continued fractionation of the interstitial melt producing low ba and sr rhyolite magma ar ar dating of feldspars and matrix glass or holocrystalline groundmass has been carried out on twelve of the units many units have a complex ar isotopic system with many samples showing evidence for inherited 40ar in the form of feldspar xenocrysts the deduced eruption ages span an age range from 650ka the eruptive history of ljosufjoll probably extends further back than this but the products of previous eruptions have since been removed by erosion or buried a syenite xenolith was dated at 1 1ma indicating that silicic alkaline magmatism has been occurring at ljosufjoll for over one million years eruptions of silicic material at ljosufjoll appear to be more common during times of rapid climate change and fluctuating ice volume

chemical studies of l chondrites vi variations with petrographic type and shock loading among equilibrated falls to study compositional trends associated with open and closed system metamorphism and or shock induced heating of the l4 6 chondrite parent s we used icpms and rnaa to quantify 51 trace elements in 48 chemically representative fall samples with these data we used graphic and two multivariate statistical methods for examining evidence for compositional differences with respect to petrographic type and degree of shock loading comparisons of mildly shocked s1 s3 l5 and l6 suites 9 and 8 chondrites respectively yield no convincing statistical evidence for a difference in trace element content our multivariate comparisons show a difference on a model dependent basis but yield indeterminate results on a model independent basis compositionally suites of strongly shocked s4 s6 and mildly shocked l4 6 chondrites 26 and 19 samples respectively can be distinguished at statistically significant levels on both model dependent and independent bases in the strongly shocked suite contents of refractory lithophiles are higher and siderophiles and volatiles are lower than those of the mildly shocked suite at moderately p 0 05 to highly significant p 0 01 levels our studies suggest that chemical differences from vaporization and loss of volatiles along with metal silicate partitioning are present from extended cooling of shock heated bodies produced by intermittent impacts especially the massive impact s that disrupted the l chondrite parent s 500 ma ago

andosolization of ferrallitic soils in the bambouto mountains west cameroon abstract soils along a toposequence 1500 2260 m on the southern slope of the volcanic bambouto mountains in western cameroon were investigated to elucidate the occurrence and development of andic properties at high altitude 1800 m in the study area the surface layer that has these properties has in the past been interpreted as a weathered volcanic ash layer overlying ferrallitic soils that developed from lava flow deposits and derived pediments physico chemical and mineralogical data demonstrate that the andic properties of the high altitude pedons result from som accumulation favoured by climate and vegetation the andosolization process affecting these profiles involves the formation of organo metallic complexes which is mediated by organic ligands and controlled by the dissolution of gibbsite and iron oxides increasing andosolization with increasing altitude due to som accumulation is well reflected by soil classification names especially by the humic qualifier for the soils below 1800 m a s l and the protoandic subqualifier for the soils at higher altitude all analysed properties show features that are incompatible with derivation of the upper part of the high altitude pedons from volcanic ash in studies of soils from similar settings care should be taken to avoid misinterpretation of surface horizons marked by environmentally conditioned development of organo metallic complexes as ash derived layers

comparing rockfall scar volumes and kinematically detachable rock masses scenario based risk assessment for rockfalls requires assumptions for different scenarios of magnitude volume the magnitude of such instabilities is related to the properties of the jointed rock mass with the characteristics of the existing unfavourably dipping joint sets playing a major role the critical factors for the determination of the maximum credible rockfall volume in a study site the forat negre in andorra are investigated the results from two previous analyses for the rockfall size distribution at this site are discussed the first analysis provides the observed size distribution of the rockfall scars and it is an empirical evidence of past rockfalls the second one calculates the kinematically detachable rock masses indicating hypothetical rockfalls that might occur in the future the later gives a maximum rockfall volume which is one order of magnitude higher because the persistence of the basal planes is overestimated the tension cracks and lateral planes interrupt systematically the basal planes exerting a control over their persistence and restricting the formation of extensive planes and large rockfall failures nonetheless the formation of basal planes across more than one spacings of tension cracks is possible and small step path failures have been observed too concluding the key factor for the determination of the maximum credible volume at the study site is the maximum realistic length of the basal planes penetrating into the rock mass their spacing and if applied the contribution of the rock bridges to the overall rock mass resistance

petrology and chemistry of two large granite clasts from the moon abstract pristine granite clasts in apollo 14 breccias 14321 and 14303 have estimated masses of 1 8 and 0 17 g respectively the 14321 clast is 60 k feldspar and 40 quartz with traces of extremely mg poor mafic silicates and ilmenite the 14303 clast is roughly 33 plagioclase 32 k feldspar 23 quartz 11 pyroxene and 1 ilmenite pyroxene and ilmenite are moderately mg rich plagioclase and pyroxene are strongly zoned both clasts are severely brecciated but monomict pristine both have abundant graphic intergrowths of k feldspar with quartz unlike the majority of similar earth rocks both clasts are devoid of hydrous phases the bulk composition of the 14321 clast is similar to those of several other lunar granitic samples but the 14303 clast is unique it bears as close a resemblance to kreep as it does to other lunar granites silicate liquid immiscibility may explain why the granites are low in ree relative to kreep

characterization of alpine rockslides using statistical analysis of seismic signals 1 seismic data analysis is a powerful tool for remote characterization of rock slope failures here we develop quantitative estimates of fundamental rockslide properties e g volume based solely on data from an existing regional seismic network we assembled a data set of twenty known rockslides in the central alps with volumes between 1 000 and 2 000 000 m3 and analyzed their corresponding seismograms common signal characteristics include emergent onsets slowly decaying tails and a triangular spectrogram shape the main component of seismic energy is contained in frequencies below 3 4 hz while higher frequency signals may be caused by block impacts location estimates were generated using automatic arrival time picks and resulted in a mean location error of 10 9 km a linear relationship for the detection limit of a rockslide as a function of volume was identified for our seismic station network to estimate rockslide volume runout distance drop height potential energy and fahrboschung angle of reach we extracted five simple metrics from each seismogram signal duration peak value of the ground velocity envelope velocity envelope area risetime and average ground velocity using multivariate linear regression the combination of duration peak envelope velocity and envelope area best estimated event parameters with r2 values ranging between 0 8 and 0 88 three new rockslides were then used to validate our method and volume runout drop height and potential energy were estimated within the correct order of magnitude when provided with a suitable data set of rockslide events our method can be easily adapted to other regions and seismic networks

origin of a unique impact melt rock the l chondrite ramsdorf we have studied a unique impact melt rock the ramsdorf l chondrite using optical and scanning microscopy and electron microprobe analysis ramsdorf contains not only clast poor impact melt begemann and wlotzka 1969 but also a chondritic portion 60 g with what appears at low magnification to be a normal well defined chondritic texture however detailed studies at high magnification show that 90 vol of the crystals in the chondritic portion were largely melted by the impact the chondrules lack normal microtextures and are ghosts of the original features the only relics from the precursor chondrules are olivine crystals which have the highest melting temperature 1620 c pyroxene rich chondrules were so extensively melted that no phenocrysts were preserved and the melt crystallized in situ before significant mixing with exterior olivine rich melts fine grained pyroxene chondrule ghosts have sharper boundaries with the matrix than porphyritic olivine and pyroxene chondrule ghosts probably because pyroxene rich melts are significantly more viscous complex textures that formed by injection of melt along cracks and fractures in relic olivines suggest that the chondritic portion of ramsdorf formed directly from petrologic type 3 4 material by strong shock we infer that ramsdorf was largely melted by shock pressures of 75 90 gpa and that chondrule ghosts and relic olivine phenocrysts were locally preserved by rapid cooling quenching was not due to the addition of cold clasts into the melt but to heterogeneous shock heating that only caused internal melting of large olivines and pyroxenes ramsdorf appears to be one of the most heavily shocked meteorites that has retained some trace of its original texture

terrestrial laser scanning of rock slope instabilities this manuscript presents a review on the application of a remote sensing technique terrestrial laser scanning tls to a well known topic rock slope characterization and monitoring although the number of publications on the use of tls in rock slope studies has rapidly increased in the last 5 10 years little effort has been made to review the key developments establish a code of best practice and unify future research approaches the acquisition of dense 3d terrain information with high accuracy high data acquisition speed and increasingly efficient post processing workflows is helping to better quantify key parameters of rock slope instabilities across spatial and temporal scales ranging from cubic decimetres to millions of cubic metres and from hours to years respectively key insights into the use of tls in rock slope investigations include a the capability of remotely obtaining the orientation of slope discontinuities which constitutes a great step forward in rock mechanics b the possibility to monitor rock slopes which allows not only the accurate quantification of rockfall rates across wide areas but also the spatio temporal modelling of rock slope deformation with an unprecedented level of detail studying rock slopes using tls presents a series of key challenges from accounting for the fractal character of rock surface to detecting the precursory deformation that may help in the future prediction of rock failures further investigation on the development of new algorithms for point cloud filtering segmentation feature extraction deformation tracking and change detection will significantly improve our understanding on how rock slopes behave and evolve perspectives include the use of new 3d sensing devices and the adaptation of techniques and methods recently developed in other disciplines as robotics and 3d computer vision to rock slope instabilities research

paleoproductivity in the equatorial indian ocean for the last 260 000 yr a transfer function based on planktonic foraminifera a principal component analysis pca of planktonic foraminifera in surface sediment of the northern equatorial indian ocean defines two major assemblages the first one dominated by globigerinoides sacculifer g ruber globigerinella aequilateralis and globoquadrina conglomerata characterizes non upwelling areas the second dominated by globigerina bulloides g falconensis and globigerinita glutinata characterizes upwelling areas the distribution of planktonic foraminiferal species in the area is mainly related to primary production pp the pca applied to core md 900963 samples defines an alternation of the two assemblages through time a non upwelling one similar to that present in the core tops and an upwelling assemblage which contains in addition neogloboquadrina dutertrei globorotalia menardii and g crassaformis equatorial indian ocean core top samples are introduced as additional rows in the pca calculated on core md 900963 samples and a transfer function is constructed correlating factorial coordinates of core tops within the range of changes occurring in core md 900963 with estimated pp values applied to the last 260 000 yr the transfer function indicates that the precession is the major orbital forcing on equatorial productivity changes and that annual pp increases by about 85 from interglacial to glacial interstadials these results are in agreement with an independent productivity index based on coccoliths direct impact of insolation on equatorial productivity could be explained by the link between southern oscillation and intensity of zonal winds which seem to lead the productivity of surface waters at the location of core md 900963

the indian monsoon and its variability for over 300 years the monsoon has been viewed as a gigantic land sea breeze it is shown in this paper that satellite and conventional observations support an alternative hypothesis which considers the monsoon as a manifestation of seasonal migration of the intertropical convergence zone itcz with the focus on the indian monsoon the mean seasonal pattern is described and why it is difficult to simulate it is discussed some facets of the intraseasonal variation such as active weak cycles break monsoon and a special feature of intraseasonal variation over the region namely poleward propagations of the itcz at intervals of 2 6 weeks are considered vertical moist stability is shown to be a key parameter in the variation of monthly convection over ocean and land as well as poleward propagations special features of the bay of bengal and the monsoon brought out by observations during a national observational experiment in 1999 are briefly described

seismic monitoring system for landslide hazard assessment and risk management at the drainage plant of the peschiera springs central italy abstract the assessment of landslide hazards and design of strategies for managing the related risk have been widely studied topics in the scientific community due to the settlements infrastructures and tourist and cultural heritage sites that may be threatened by deformations involving unstable slopes engineering geological and geophysical techniques have been recently integrated in multidisciplinary approaches to study gravity induced slope instabilities and monitor their evolution the slope that hosts the peschiera springs drainage plant central italy is involved in a mass rock creep process associated with deep karst dissolution due to the importance of this infrastructure which provides water to the rome aqueduct an accelerometric network was installed in 2008 and a nanoseismic array was added in 2014 in this paper data recorded by the nanoseismic array were used to locate 397 microseismic events related to the slope instability process distinguished into two types with different waveforms 16 failures and 381 collapses the failures were distributed throughout the slope while the collapses exhibited two spatially separate clusters below the groundwater level at a depth where karst processes produce cavities the clusters were analysed as two distinct microseismic sources characterised by specific frequency magnitude curves of events that describe their attitude to produce events of different magnitudes regarding the accelerometric network an automated procedure was developed for quickly analysing the seismic records which include signals from teleseisms and near to far field earthquakes that can induce deformation in the landslide involved slope the results obtained by the two seismic monitoring systems were integrated with the aim of implementing a landslide hazard matrix based on the statistical frequency of the occurrence of such events and their probability of exceedance during a reference period providing a useful tool for managing the related landslide risk

tropical climates at the last glacial maximum a new synthesis of terrestrial palaeoclimate data i vegetation lake levels and geochemistry palaeodata in synthesis form are needed as benchmarks for the palaeoclimate modelling intercomparison project pmip advances since the last synthesis of terrestrial palaeodata from the last glacial maximum lgm call for a new evaluation especially of data from the tropics here pollen plant macrofossil lake level noble gas from groundwater and delta 18 o from speleothems data are compiled for 18 2 ka c 14 32 degrees n 33 degrees s the reliability of the data was evaluated using explicit criteria and some types of data were re analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month mtco mean annual temperature mat plant available moisture pam and runoff p e cold month temperature mat anomalies from plant data range from 1 to 2 k near sea level in indonesia and the s pacific through 6 to 8 k at many high elevation sites to 8 to 15k in s china and the se usa mat anomalies from groundwater or speleothems seem more uniform 4 to 6 k but the data are as yet sparse a clear divergence between mat and cold month estimates from the same region is seen only in the se usa where cold air advection is expected to have enhanced cooling in winter regression of all cold month anomalies against site elevation yielded an estimated average cooling of 2 5 to 3 k at modern sea level increasing to approximate to 6 k by 3000m how ever neotropical sites showed larger than the average sea level cooling 5 to 6 k and a non significant elevation effect whereas w and s pacific sites showed much less sea level cooling 1 k and a stronger elevation effect these findings support the inference that tropical sea surface temperatures ssts were lower than the climap estimates but they limit the plausible average tropical sea surface cooling and they support the existence of climap like geographic patterns in sst anomalies trends of pam and lake levels indicate wet lgm conditions in the w usa and at the highest elevations with generally dry conditions elsewhere these results suggest a colder than present ocean surface producing a weaker hydrological cycle more arid continents and arguably steeper than present terrestrial lapse rates such linkages are supported by recent observations on freezing level height and tropical ssts moreover simulations of greenhouse and lgm climates point to several possible feedback processes by which low level temperature anomalies might be amplified aloft

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

occurrence of sombric like subsurface a horizons in some andic soils of the nilgiri hills southern india and their palaeoecological significance this paper deals with four pedons three fulvudands and one andic haplorthox located at high elevations 2000 2400 m a s l in the nilgiri hills on an old laterized surface of south india and characterized by thick 50 100 cm epipedons whose colour tends to darken with depth in two of them the colour contrast between the top and the bottom a horizons was so well expressed that they were morphologically very similar to the african oxisols reported to have sombric subsurface horizons soil organic matter som of the different selected a horizons was characterized by its mean residence time mrt and its delta 13 c value whereas their humic acids has were examined by techniques that made it possible to determine their chemical composition and their chromatic properties it was found that the darker colour of the subsurface a horizons of these soils was related to three joined characteristics a som delta 13 c signature indicating a c4 type vegetation i e a grassland type origin the presence of humic acids belonging to the a type i e melanic category of kumada kurnada k 1987 chemistry of soil organic matter developments in soil science elsevier tokyo and large mean residence time values in contrast the top a horizons had a more recent som mainly inherited from a c3 type vegetation and humic acids has that were less condensed than the a type has it was also found that where the presence of sombric like subsurface a horizons was the most evident the vegetation change recorded by the soils i e the change from a grassland type vegetation towards a c3 type vegetation was expressed on the thickest part of their epipedon these observations led us to propose that the occurrence of sombric like subsurface a horizons resulted from the following sequence of events i an exceptionally thick accumulation of organic matter deriving from grassland followed by ii its progressive replacement by less dark organic matter derived from a c3 type vegetation this proposal was found to be in reasonable agreement with the history of the vegetation changes experienced by the nilgiri hills since the end of the pleistocene on the other hand it is also very similar to one of the hypotheses proposed by van wambeke van wambeke a 1992 soils of the tropics properties and appraisal mcgraw hill new york to explain the frequent occurrence of sombric horizons in the oxisols and ultisols of the high altitude areas of central africa c 2003 elsevier science b v all rights reserved

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

late holocene climate in the lower narmada valley gujarat western india inferred using sedimentary carbon and oxygen isotope ratios we report the late holocene climate and vegetation of the lower narmada valley gujarat western india as inferred from the stable carbon and oxygen isotopic composition 13c and 18o of sediment

the characterization of steady state in earth surface systems findings from the gradient modelling of an indian climosequence abstract gradient modelling of a steep ecocline in south india has highlighted a suite of landscape units which appear to be entirely ordained by a simple water balance index this univariate climofunction is reflected in vegetation landform weathering and soil patterns although the vegetation successions are the most spectacular consistent pedogeomorphological trends were identified at several embedded scales of reality at the microscopic scale the existence of illite rich saprolite situated between the kaolinite dominated and smectite dominated core areas of the climosequence so far a missing mineralogical link only predicted by geochemical theory was effectively verified by field evidence at the megascopic scale the variation in topographic texture from polyconvex to polyconcave land systems via a convexo concave transition zone also suggests a strong relationship between hydroclimatic budgets and landforms such an exceptional environmental cabinet is well suited to reexamining other benchmark climosequences of the tropics and to readdressing the debated theories of climatic geomorphology by a discussion on the applicability of climax and steady state to tropical landforms

silica polymorphs in lunar granite implications for granite petrogenesis on the moon granitic lunar samples largely consist of granophyric intergrowths of silica and k feldspar the identification of the silica polymorph present in the granophyre can clarify the petrogenesis of the lunar granites the presence of tridymite or cristobalite would indicate rapid crystallization at high temperature quartz would indicate crystallization at low temperature or perhaps intrusive slow crystallization allowing for the orderly transformation from high temperature silica polymorphs tridymite or cristobalite we identify the silica polymorphs present in four granitic lunar samples from the apollo 12 regolith using laser raman spectroscopy typically lunar silica occurs with a hackle fracture pattern we did an initial density calculation on the hackle fracture pattern of quartz and determined that the volume of quartz and fracture space is consistent with a molar volume contraction from tridymite or cristobalite both of which are less dense than quartz moreover we analyzed the silica in the granitic fragments from apollo 12 by electron probe microanalysis and found it contains up to 0 7 wt tio2 consistent with initial formation as the high temperature silica polymorphs which have more open crystal structures that can more readily accommodate cations other than si the silica in apollo 12 granitic samples crystallized rapidly as tridymite or cristobalite consistent with extrusive volcanism the silica then inverted to quartz at a later time causing it to contract and fracture a hackle fracture pattern is common in silica occurring in extrusive lunar lithologies e g mare basalt the extrusive nature of these granitic samples makes them excellent candidates to be similar to the rocks that compose positive relief silicic features such as the gruithuisen domes

inferred attenuation from site effect corrected t phases recorded on the island of hawaii coda site amplification factors are used to eliminate the site effect from records of three circum pacifict phases recorded by the hawaiian volcano observatory hvo network on the island of hawaii observedt phase amplitudes across the island generally decrease with increasing distance from the conversion point where acoustic waves in the sofar channel become seismic waves propagating through the crust however the decay of the observedt phase signal across the island is not regular in regions of dense station coverage in particular the kilauea caldera region we divide the maximum observedt phase amplitudes at a given station by the coda site amplification factor obtained for the same station and frequency band 3 0hz the distribution of these amplitudes reveals a smooth pattern over the entire island the distance over which the site effect correctedt phase amplitude decreases by one half combined with the apparent velocity of propagation oft phases across the island allows for an approximate determination of near surfaceq over much of the island of hawaii we found a region of lowq in the kilauea summit area q 30 and east rift zone q 60 with considerably higherq in the kaoiki and northern portions of the island q 150 to 200 the lowq values obtained in the kilauea summit region and east rift zone are significantly lower than estimates of codaq in the same region suggestingt phases may be sampling the earth s near surface properties

characterization and origin of aluminous a type granites from the lachlan fold belt southeastern australia the metaluminous to weakly peraluminous a type granites of the lachlan fold belt are a distinctive group of igneous rocks on the basis of chemical and mineralogical criteria those granites that contain 65 72 sio2 can be distinguished from other types on the basis of higher abundances of fetotal fetotal mg high field strength elements trivalent rare earth elements ga and zn mineralogically they contain fe rich hydrous mafic minerals and primary ilmenite and hence are reduced relative to the ni nio buffer however the extremely felsic a type granites sio2 72 have the same chemical and mineralogical characteristics as felsic fractionated i type granites recent analyses indicate that the lachlan fold belt a type granites have sc f alkali element trace transition element and h2o contents similar to those of other unfractionated i type granites rb sr and nd sm isotopic compositions are highly variable probably reflecting source region heterogeneity the metaluminous to weakly peraluminous a type granites of the lachlan fold belt are distinct from peralkaline rocks in terms of chemical composition petrography and field associations although these rocks have been grouped together as a single type in current classification schemes we propose that the metaluminous to weakly peraluminous a type granites such as those of the lachlan fold belt should be defined as aluminous a type granites and should not be grouped with peralkaline granites the lachlan fold belt aluminous a type granites have relatively high calculated zircon saturation temperatures we suggest that these granites were produced by high temperature partial melting of a felsic infracrustal source

a 200 ka pollen and oxygen isotopic record from two sediment cores from the eastern arabian sea abstract we present here a pollen record from the northern indian ocean that goes back to 200 ka the boundary between marine isotopic stages mis 7 and 6 pollen oxygen isotopic composition and organic carbon have been examined for two sediment cores from the eastern arabian sea 15 02 n and 71 41 e 13 16 n and 71 00 e to reconstruct the long term palaeoclimate and palaeovegetation of the indian subcontinent oxygen isotope data suggest that glacial periods mis 2 4 and 6 are characterised by low precipitation because of a weak southwest monsoon and a strong northeast monsoon in contrast interglacial periods mis 1 3 and 5 are marked by high fresh water input resulting from a strong southwest monsoon during the last glacial interglacial cycle sea surface temperature and surface salinity changed as a result of variations in the evaporation precipitation e p balance throughout the core the dominant pollen types are poaceae and chenopodiaceae and or amaranthaceae 50 their dominance during glacial periods mis 2 4 and 6 suggests that the climate was cold and dry this dominance is also suggestive of salinity tolerant vegetation colonizing large areas near seashore due to lower sea level or high e p conditions during interglacial periods mis 1 3 and 5 when there was high precipitation the arid taxa were sparse whereas poaceae and piperaceae were abundant hence chenopodiaceae and or amaranthaceae and artemisia are suggestive of cold and arid semi arid climate and poaceae and piperaceae of warm and wet conditions mangrove pollen is not well represented in the cores

analysis of rock fall and rock fall avalanche seismograms in the french alps this study reviews seismograms from 10 rock fall events recorded between 1992 and 2001 by the permanent seismological network sismalp in the french alps a new seismic magnitude scale was defined which allowed us to compare and classify g round motion vibrations generated by these alpine rock falls each rock fall has also been cha racterized by its ground motion duration t30 at an epicentral distance of 30 km no relation was found between rock fall parameters fall height runout distance volume potential energy and rock fall s eismic magnitudes derived from seismogram amplitudes on the other hand the signal duration t30 shows a rough correlation with the potential energy and the runout distance highlighting the co ntrol of the propagation phase on the signal length the signal analysis suggests the existence of at le ast two distinct seismic sources one corresponding to the initial rupture associated with an elastic r ebound during the detachment and the other one generated by the rock impact on the slope although the fall phenomenon includes other complex processes fragmentation of the block interaction with topography plastic deformation during and after impact 2d finite element simulations of thes e two seismic sources are able to retrieve the main seismogram characteristics

reconstructing sea surface temperature and salinity using δ 18 o and alkenone records the oxygen isotope 18o composition of foraminiferal tests from deep sea sediments is widely used as a palaeoclimate proxy but it includes contributions from sea surface temperature global ice volume and local salinity which are difficult to separate recently a new technique for deriving palaeotemperatures has been developed which is based on the abundance ratios of unsaturated alkenones in phytoplankton algae1 2 here we use a combination of oxygen isotope and alkenone records in a deep sea core from the juncture of the arabian sea and the bay of bengal to extract the salinity signal from the former record variations in salinity are related to the balance between evaporation and precipitation3 and are thus a sensitive indicator of climate change our 170 kyr salinity record enables us to reconstruct changes in the indian monsoon over this period considerably extending earlier studies which reached back to 18 kyr ago 4 8 like these previous studies we find that large variations in the monsoon occurred during the transition from the last glacial period to the present interglacial but our results also provide a view of the monsoon throughout the last glacial and demonstrate the potential of this approach for reconstructing palaeosalinity

identifying and mapping potentially adverse discontinuities in underground excavations using thermal and multispectral uav imagery abstract geotechnical mapping rock mass characterization and inspections of underground excavations are critical to ensuring that excavation geometry and ground support design are appropriate for stable conditions a lack of access poor timing or hazardous conditions are all factors that can prohibit engineering personnel from collecting high quality data in the field advances in unmanned aerial vehicles uav and portable sensor technology now allow engineering personnel to remotely capture data from underground workings that can be used for developing designs generating inputs for analyses and making more informed decisions ground falls are a source of many accidents in the underground environment and they are the focus of many geotechnical investigations and analyses in this study the authors investigated how portable uav mounted thermal and multispectral imagers could be used to detect and quantify adverse geological discontinuities in hard rock masses that are structurally controlled multiple thermal multispectral rgb red green and blue and lidar light detection and ranging data sets were captured from 5 flights in sub level open stopes at the barrick golden sunlight mine in the state of montana in the western united states of america using off the shelf software the thermal rgb and multispectral images were processed to create individual three dimensional point clouds and meshes which were georeferenced using the lidar data discontinuities identified in the three dimensional point clouds and meshes were mapped using tools found in the freeware cloudcompare one of the thermal models identified wedges that had developed in the crown pillar of an open stope and 4 of the multispectral models contained enough detail for mapping individual discontinuities the results of this investigation indicate that these portable imagers are viable tools that can be used to aid engineering personnel in identifying and mapping adverse geological discontinuities and unique rock mass composition the techniques for capturing processing and interpreting thermal and multispectral imagery captured in underground excavations are described in this paper and can be used as the basis for future investigations at individual underground sites

non mare silicic volcanism on the lunar farside at compton belkovich non basaltic volcanism is rare on the moon and has been found predominantly on the lunar nearside analysis of lunar reconnaissance orbiter camera images and spectral data reveal the presence of compositionally evolved non basaltic volcanism on the lunar farside

determination of the seismic signatures of landslides in soft soils a methodology based on a field scale shear box abstract we present a novel field experimental setup that can be used for studying the characteristics of landslide seismicity the setup consists of a concrete filled with soil cylinder that moves along a surficial soil corridor the emitted seismic signals are due to soil friction the cylinder acts as an upscaled sheer box allowing control over a number of parameters the magnitude of normal stress on the failure plane the degree of saturation and the type of soil this allows for the simulation of soil friction within or between different geological layers under different conditions results are site specific but can be easily reproduced for any geological environment we validate this methodology by comparing the spectral characteristics of the signals emitted by the movement of the cylinder to those induced by a controlled failure of a 2 5 m high vertical face at a nearby site with very similar geology we find a very good agreement between the two this methodology can be used as a site investigation tool for the optimization of the deployment geometry of seismic networks for landslide monitoring as well as to inform machine learning algorithms on automatic detection and classification of recorded signals during seismic monitoring of landslides

soils and climatic geomorphology on the karnataka plateau peninsular india abstract as a result of extensive field reconnaissance in southern india a geographical traverse across the planation surface of the karnataka uplands which lie in the rainshadow of the western ghats was selected to assess the consequences of a steep rainfall gradient on soil and landform patterns the study of the traverse described in detail reveals a characteristic progression of soil type and wash divide form from the high rainfall to the semi arid end of the continuum and invites a critical reappraisal of classical notions in climatic geomorphology and the soil sciences the assumption that alternations of wet and dry climates are necessary to achieve planation is given special consideration and the often held belief that kaolinite minerals are diagnostic of humid palaeoclimates when found in a semi arid climate is challenged the findings for the indian traverse are set against the better known data for west africa where the rainfall range between the gulf of guinea and the sahel is comparable with that observed in the south western deccan differences outweighing similarities attention is drawn to the possibility that tectonic regime which also controls the degree of landscape stripping is a major key to understanding the climatic geography of soils the tread of planation surfaces and the shape of hillslopes from one region of the tropics to another

friction weakening in granular flows deduced from seismic records at the soufriere hills volcano montserrat accurate modeling of rockfalls and pyroclastic flows is still an open issue partly due to a lack of measurements related to their dynamics using seismic data from the soufriere hills volcano montserrat and granular flow modeling we show that the power laws relating the seismic energy e s to the seismic duration t s and relating the loss of potential energy e p to the flow duration t f are very similar like the power laws observed at piton de la fournaise reunion island observations showing that t f t s suggest a constant ratio e s e p 10 5 this similarity in these two power laws can be obtained only when the granular flow model uses a friction coefficient that decreases with the volume transported furthermore with this volume dependent friction coefficient the simulated force applied by the flow to the ground correlates well with the seismic energy highlighting the signature of this friction weakening effect in seismic data

automated identification location and volume estimation of rockfalls at piton de la fournaise volcano since the collapse of the dolomieu crater floor at piton de la fournaise volcano la reunion in 2007 hundreds of seismic signals generated by rockfalls have been recorded daily at the observatoire volcanologique du piton de la fournaise ovpf to study rockfall activity over a long period of time automated methods are required to process the available continuous seismic records we present a set of automated methods designed to identify locate and estimate the volume of rockfalls from their seismic signals the method used to automatically discriminate seismic signals generated by rockfalls from other common events recorded at ovpf is based on fuzzy sets and has a success rate of 92 a kurtosis based automated picking method makes it possible to precisely pick the onset time and the final time of the rockfall generated seismic signals we present methods to determine rockfall locations based on these accurate pickings and a surface wave propagation model computed for each station using a fast marching method these methods have successfully located directly observed rockfalls with an accuracy of about 100 m they also make it possible to compute the seismic energy generated by rockfalls which is then used to retrieve their volume the methods developed were applied to a data set of 12 422 rockfalls that occurred over a period extending from the collapse of the dolomieu crater floor in april 2007 to the end of the undervolc project in may 2011 to identify the most hazardous areas of the piton de la fournaise volcano summit

dynamics of the monsoon in the equatorial indian ocean over the last 260 000 years abstract the coccolithophorids are excellent indicators of the variations in ocean productivity as an example the relative abundance of florisphaera profunda a species which lives exclusively in the deepest part of the photic zone constitutes a reliable monitor of the depth of the nutricline as a function of climatic variability productivity in the indian ocean is closely linked with the monsoon its intensity affects the depth of the mixing zone which deepens as the wind stress increases during the monsoon season the nutricline is shallow resulting in a higher productivity the variations in composition of coccolith assemblages in well dated oceanic sediments allows to describe the dynamics of productivity and therefore the fluctuation of the monsoon intensity core md900963 was retrieved in the equatorial indian ocean east of the maldives at a water depth of 2400 m a precise chronology was established by fine tuning the high resolution 18o record with the specmap stack coccoliths were counted from samples taken at 10 cm intervals in the core providing a resolution of 2000 years for the last 260 000 years the productivity estimates made from coccolith counts show that productivity varied greatly in the maldives area during this time the variations of the coccolith productivity index match the variations of the organic carbon content in the sediment spectral analysis reveals strong precessional cycles and weak obliquity and eccentricity cycles this implies that the solar radiation has a dominant effect on the monsoon variability south of india the productivity maxima occur during even numbered 18o stages this may indicate that the productivity events are related to increase of the winter monsoon however the analysis of the phase between the palaeoproductivity and seasonal solar radiation curves calculated for the past 260 000 years suggest an alternative hypothesis the westerlies which blow in april in the maldives area there the onset of the monsoon is in advance on the arabian sea would have a major effect on productivity since the insolation curve of the end of march at 5 n is in perfect phase with the paleoproductivity record for the last 260 000 years

coarse fraction fluctuations in pelagic carbonate sediments from the tropical indian ocean a 1500 kyr record of carbonate dissolution appendix table al is available with entire article onmicrofiche order from the american geophysical union 2000florida avenue n w washington d c 20009 documentp94 001 2 50 payment must accompany order we examined coarse fraction contents of pelagic carbonates deposited between 2000 and 3700 m water depth in the tropical indian ocean using ocean drilling program odp sites 722 owen ridge arabian sea and 758 ninetyeast ridge eastern equatorial indian ocean and four giant piston cores collected by the french r v marion dufresne during the seymama expedition over the last 1500 kyr coarse fraction records display high amplitude oscillations with an irregular wavelength on the order of 500 kyr these oscillations can be correlated throughout the entire equatorial indian ocean from the seychelles area eastward to the ninetyeast ridge and into the arabian sea changes in grain size mainly result from changes in carbonate dissolution as evidenced by the positive relationship between coarse fraction content and a foraminiferal preservation index based on test fragmentation the well known mid bruhes dissolution cycle represents the last part of this irregular long term dissolution oscillation the origin of this long term oscillation is still poorly understood our observations suggest that it is not a true cycle it has an irregular wavelength and we propose that it may result from long term changes in ca flux to the ocean sites 722 and 758 18o records provide a high resolution stratigraphy that allows a detailed intersite comparison of the two coarse fraction records over the last 1500 kyr site 722 2030 m lies above the present and late pleistocene lysocline the lysocline shoaled to the position of site 758 2925 m only during the interglacial intervals that occurred between about 300 and 500 ka peterson and prell 1985a despite these supralysoclinal positions of the two sites short term changes in coarse fraction contents are correctable from one site to another and probably result from regional or global dissolution pulses by stacking the normalized coarse fraction records from sites 722 and 758 we constructed a composite coarse fraction index ccfi curve in which most of the local signals cancelled out the last 800 kyr of this curve appear to compare extremely well with the composite dissolution index curve from core v34 53 ninetyeast ridge which unambiguously records past variations of carbonate dissolution in the equatorial indian ocean peterson and prell 1985a in the late pleistocene the ccfi variations are mainly associated with glacial interglacial changes they show strong 100 and 41 kyr periodicities but no clear precession related periodicities as proposed earlier by peterson and prell 1985a the lack of precession frequencies may suggest that the regional carbonate dissolution signal is driven by changes in deepwater circulation we cannot totally reject the possibility however that low temporal resolution and or bioturbation degrade somehow the precessional signal at odp sites 722 and 758 in contrast spectral density of dissolution cycles in the giant 53 m long piston core md900963 maldives area displays clear maxima centered on the precession frequencies 23 and 19 kyr 1 as well as on the kyr 1 frequency but shows little power at the 100 kyr 1 frequency these high frequency changes most probably result from changes in surface productivity associated with monsoon variability dissolution at this site may be ultimately controlled by the oxidation of organic matter which appears to be incorporated into the sediments in greater quantity during periods of weak sw monsoon and or increased dry ne monsoon

frequency dependent lg wave attenuation in northern morocco abstract frequency dependent attenuation q 1 in the crust of northern morocco is estimated from lg wave spectral amplitude measurements every quarter octave in the frequency band 0 8 to 8 hz this study takes advantage of the improved broadband data coverage in the region provided by the deployment of the iberarray seismic network earthquake data consist of 71 crustal events with magnitudes 4 m b 5 5 recorded on 110 permanent and temporary seismic stations between january 2008 and december 2013 with hypocentral distances between 100 and 900 km 1274 high quality lg waveforms provide dense path coverage of northern morocco crossing a region with a complex structure and heterogeneous tectonic setting as a result of continuous interactions between the african and eurasian plates we use two different methods the coda normalization cn analysis that allows removal of the source and site effects from the lg spectra and the spectral amplitude decay sad method that simultaneously inverts for source site and path attenuation terms the cn and sad methods return similar results indicating that the lg q models are robust to differences in the methodologies larger errors and no significant frequency dependence are observed for frequencies lower than 1 5 hz for distances up to 400 km and the frequency band 1 5 hz 4 5 the model functions q f 529 22 23 f 1 5 0 23 0 06 and q f 457 7 7 f 1 5 0 44 0 02 are obtained using the cn and sad methods respectively a change in the frequency dependence is observed above 4 5 hz for both methods which may be related to the influence of the sn energy on the lg window the frequency dependent q 1 estimates represent an average attenuation beneath a broad region including the rif and tell mountains the moroccan and algerian mesetas the atlas mountains and the sahara platform structural domains and correlate well with areas of moderate seismicity where intermediate q values have been obtained

a δ 13 c record of late quaternary climate change from tropical peats in southern india stable isotope ratios of carbon in soils or lake sediments1 3 and of oxygen and hydrogen in peats4 5 have been found to reflect past moisture variations and hence to provide valuable palaeoclimate records previous applications of the technique to peat have been restricted to temperate regions largely because tropical climate variations are less pronounced making them harder to resolve here we present a 13c record spanning the past 20 kyr from peats in the nilgiri hills southern india because the site is at high altitude 2 000 m above sea level it is possible to resolve a clear climate signal we observe the key climate shifts that are already known to have occurred during the last glacial maximum 18 kyr ago and the subsequent deglaciation in addition we observe an arid phase from 6 to 3 5 kyr ago and a short wet phase about 600 years ago the latter appears to correspond to the mediaeval warm period which previously was believed to be confined to europe and north america6 7 our results therefore suggest that this event may have extended over the entire northern hemisphere

formation conditions of igneous regions in ordinary chondrites chico rose city and other heavily shocked h and l chondrites we report microprobe and radiochemical neutron activation analysis rnaa data for hosts and igneous inclusions in the heavily shocked ordinary chondrites rose city h5 yanzhuang h6 farmington l5 malakal l5 chantonnay l6 chico l6 and tuan tuc l6 based on these analytical results equilibrium crystallization calculations ghiorso and sack 1995 phase equilibrium analysis e g sack and ghiorso 1994a b sack et al 1994 and experimental cooling rate studies e g walker et al 1976 we have assessed the metamorphic and magmatic histories of these seven heavily shocked chondrites we infer that 1 unfractionated chondritic liquids were intruded to depths 0 1 km in the parent asteroid of rose city 2 early chondritic liquids experiencing 5 10 olivine fractionation were erupted onto the surface of the parent asteroid s of yanzhuang and chantonnay and 3 near surface crystallization is also indicated for the liquids in tuan tue and farmington with chico and malakal crystallizing at slightly greater depths in all but chantonnay liquids appear to have derived from melting of chondrite types corresponding to their hosts in the l chondrite chantonnay the intrusive liquids derive from melting an h chondrite source region in which chondritic melts were stored for a sufficient time to produce pigeonite in zoned pyroxene xenocrysts heating effects are also reflected in the trace element contents of the chondrites our rnaa data for rose city seem to reflect only the siderophile lithophile fractionation evident in the metal distribution the yanzhuang rnaa data are generally similar to those of other h chondrites severe shock not involving phase transport seems to leave h chondrites unaffected compositionally contents of the four most mobile elements cd bi t1 in and cs in chico indicate loss so that this assemblage experienced extended low temperature cooling after injection of dike material into the chico host rnaa data for the other four l chondrites examined indicate more rapid cooling

detection and location of rock falls using seismic and infrasound sensors abstract we deployed seismic and infrasound sensors at a historically active cliff in yosemite valley for the purpose of detecting and locating rock falls at local

a comment on titaniq under pressure the effect of pressure and temperature on the solubility of ti in quartz by jay b thomas e bruce watson frank s spear philip t shemella saroj k nayak and antonio lanzirotti trace concentrations of ti in quartz are used to indicate the pressure and temperature conditions of crystallization in the titaniq geothermobarometer of thomas et al contrib miner petrol 160 743 759 2010 it utilises the partitioning of ti into quartz as an indicator of the pressures and or temperatures of crystal growth for a given value of tio2 activity in the system if temperatures are inferred to 20 c pressure is constrained to 1 kbar and vice versa there are significant contrasts however between the conclusions from titaniq and those for natural quartz as well as other mineral phases in volcanic rocks application of the titaniq model to quartz from the 27 ka oruanui and 760 ka bishop high silica rhyolites where the values of t p and tio2 activity are constrained by other means fe ti oxide equilibria melt inclusion entrapment pressures in gas saturated melts melt and amphibole compositions yields inconsistent results if realistic values are given to any two of these three parameters then the value of the third is wholly unrealistic the model yields growth temperatures at or below the granite solidus pressures in the lower crust or upper mantle or tio2 activities inconsistent with the mineralogical and chemical compositions of the magmas cl imagery and measurements of ti and other elements in quartz are of great value in showing the growth histories and changes in conditions experienced by crystals but direct linkages to p t conditions during crystal growth cannot be achieved

late quaternary vegetation dynamics in the southern amazon basin inferred from carbon isotopes in soil organic matter abstract carbon isotopes of soil organic matter som were used to evaluate and establish the chronology of the vegetation dynamics of an ecosystem presently composed of savannas surrounded by forests the study was carried out on a 200 km transect along highway br 319 on the border of amazonas and rondonia states in southern amazon brazil large ranges in 13 c values were observed in som collected from profiles in the savanna 27 to 14 and forest regions 26 to 19 reflecting changing distribution of 13 c depleted c 3 forest and 13 c enriched c 4 savanna vegetation in response to climate change these results indicate that from about 17 000 to 9000 14 c yr b p the study area was covered by forest vegetation between approximately 9000 and 3000 14 c yr b p savanna vegetation expanded at the expense of the forest although the expansion of savanna did not occur with the same intensity along the study transect this process was very clearly registered by 13 c enrichment in the som since 3000 14 c yr b p the carbon isotope data suggest that forested regions have expanded this study adds to the mounting evidence that extensive forested areas existed in the amazon during the last glaciation and that savanna vegetation expanded in response to warm and dry conditions during the early to middle holocene

microseismic investigation of an unstable mountain slope in the swiss alps 1 risks associated with unstable rocky slopes are growing as a result of climate change and rapid expansions of human habitats and critical infrastructure in mountainous regions to improve our understanding of mountain slope instability we developed a microseismic monitoring system that operates autonomously in remote areas afflicted by harsh weather our microseismic system comprising 12 three component geophones was deployed across 60 000 m 2 of rugged crystalline terrain above a huge 30 million m 3 recent rockfall in the swiss alps during its 31 month lifetime signals from 223 microearthquakes with approximate moment magnitudes ranging from 2 to 0 were recorded determining the hypocenters was challenging for several reasons 1 p wave velocities were highly heterogeneous varying abruptly from 3 8 km s 2 first break picks were either inaccurate or lacking for some microearthquakes 3 there were no reliable s wave picks 4 numerous microearthquakes occurred just outside the network boundaries these issues were addressed by using a three dimensional 3 d p wave velocity model of the mountain slope determined from refraction tomography in a nonlinear inversion for hypocenter parameters and their probability density functions recordings from geophones at different altitudes and in boreholes constrained microearthquake depth estimates most microearthquakes were concentrated within 50 100 m of the surface in two zones one that followed the recent rockslide scarp and one that spanned the volume of highest fracture zone fault density these two active zones delineated a mass of rock that according to geodetic measurements has moved toward the scarp at 1 2 cm yr

trace element and textural evidence favoring lunar not terrestrial origin of the mini granite in apollo sample 14321 abstract the 14321 lunar granite 14321g has recently been reinterpreted bellucci et al 2019 as a piece of the hadean earth impact transported to the moon in principle samples of such derivation may afford important insights into the nature of earth s hadean crust we have tested the terrestrial provenance hypothesis by comparing trace element data from 14321g versus other lunar evolved rocks and a large data base for terrestrial granites volatile trace metals zn ga and ge are depleted in 14321g below the terrestrial granite ranges and relative to the terrestrial granite averages by factors of 27 2 0 and 18 respectively evidence from shocked chondrites martian meteorites and impact shock studies in general indicates that such major depletions are unlikely to develop without near complete shock melting which clearly did not occur in the mostly still crystalline 14321g moreover other aspects of compositional disparity between 14321g and terrestrial granites involve exclusively refractory trace elements compared to terrestrial granites of similarly high ba content 14321 is enriched in ta by a factor of 10 and the few terrestrial granites that are as ta rich as 14321 have 10 times lower ba the refractory element ratio lu sm is also close to 10 times higher in 14321g than in terrestrial granites of similarly high ba content other highly evolved lunar rocks felsites strongly resemble 14321g in all these respects we conclude that 14321g is probably of wholly lunar derivation this finding stands in contradiction to a recent inference from ti in quartz modeling bellucci et al 2019 that 14321g crystallized at a pressure of 0 69 gpa the geodynamically limited moon was presumably never capable of forming or burying such a highly granitic material 100 km below the base of its crust nor of excavating material from such a depth to the surface

dynamics of the bingham canyon rock avalanches utah usa resolved from topographic seismic and infrasound data the 2013 bingham canyon mine rock avalanches represent one of the largest cumulative landslide events in recorded u s history and provide a unique opportunity to test remote analysis techniques for landslide characterization here we combine aerial photogrammetry surveying topographic reconstruction numerical runout modeling and analysis of broadband seismic and infrasound data to extract salient details of the dynamics and evolution of the multi phase landslide event our results reveal a cumulative intact rock source volume of 52 mm3 which mobilized in two main rock avalanche phases separated by 1 5 h we estimate the first rock avalanche had 1 5 2 times greater volume than the second each failure initiated by sliding along a gently dipping 21 highly persistent basal fault before transitioning to a rock avalanche and spilling into the inner pit the trajectory and duration of the two rock avalanches were reconstructed using runout modeling and independent force history inversion of intermediate period 10 50 s seismic data intermediate and shorter period 1 50 s seismic data were sensitive to intervals of mass redirection and constrained finer details of the individual slide dynamics back projecting short period 0 2 1 s seismic energy we located the two rock avalanches within 2 and 4 km of the mine further analysis of infrasound and seismic data revealed that the cumulative event included an additional 11 smaller landslides volumes 104 105 m3 and that a trailing signal following the second rock avalanche may result from an air coupled rayleigh wave our results demonstrate new and refined techniques for detailed remote characterization of the dynamics and evolution of large landslides

ejection of martian meteorites we investigated the transfer of meteorites from mars to earth with a combined mineralogical and numerical approach we used quantitative shock pressure barometry and thermodynamic calculations of post shock temperatures to constrain the pressure temperature conditions for the ejection of martian meteorites the results show that shock pressures allowing the ejection of martian meteorites range from 5 to 55 gpa with corresponding post shock temperature elevations of 10 to about 1000 c with respect to shock pressures and post shock temperatures an ejection of potentially viable organisms in martian surface rocks seems possible a calculation of the cooling time in space for the most highly shocked martian meteorite allan hills alh 77005 was performed and yielded a best fit for a post shock temperature of 1000 c and a meteoroid size of 0 4 to 0 6 m the final burial depths of the sub volcanic to volcanic martian rocks as indicated by textures and mineral compositions of meteorites are in good agreement with the postulated size of the potential source region for martian meteorites during the impact of a small projectile 200 m as defined by numerical modeling artemieva and ivanov 2004 a comparison of shock pressures and ejection and terrestrial ages indicates that on average highly shocked fragments reach earth crossing orbits faster than weakly shocked fragments if climatic changes on mars have a significant influence on the atmospheric pressure they could account for the increase of recorded ejection events of martian meteorites in the last 5 ma

complex polarization analysis of particle motion knowledge of particle motion polarization aids in identifying phases on three component seismograms the scheme of montalbetti and kanasewich 1970 is extended to analytic three component seismograms where the imaginary part of the signal is the hilbert transform of the real part this scheme has only one free parameter the length of the time window over which the polarization parameters are estimated so it can be applied in a routine way to three component data the azimuth and dip of the direction of maximum polarization and the degree of elliptical polarization as a function of time for the seismograms are obtained polarization analysis of strong motion data from the 1971 san fernando earthquake aids in the discrimination between wave types which is important for the understanding of the complicated earthquake induced shaking observed in basins most arrivals are incident on the receivers in the direction of the back azimuth to the epicenter which suggests that despite the complicated motions two dimensional finite difference methods are sufficient to understand the effect on seismic waves of the los angeles and san fernando basins vidale and helmberger 1986b

titaniq recrystallized experimental confirmation of the original ti in quartz calibrations several studies have reported the p t dependencies of ti in quartz solubility and there is close agreement among three of the four experimental calibrations new experiments were conducted in the present study to identify potential experimental disequilibrium and to determine which ti in quartz solubility calibration is most accurate crystals of quartz rutile and zircon were grown from sio2 tio2 and zrsio4 saturated aqueous fluids in an initial synthesis experiment at 925 c and 10 kbar in a piston cylinder apparatus a range of quartz crystal sizes was produced in this experiment both large and small examples were analyzed by electron microprobe to determine whether ti concentrations are correlated with crystal size cathodoluminescence images and epma measurements show that intercrystalline and intracrystalline variations in ti concentrations are remarkably small regardless of crystal size the average ti in quartz concentration from the synthesis experiment is 392 1 ppmw ti which is within 95 confidence interval of data from the 10 kbar isobar of wark and watson contrib mineral petrol 152 743 754 2006 and thomas et al contrib mineral petrol 160 743 759 2010 as a cross check on the ti in quartz calibration we also measured the concentration of zr in rutile from the synthesis experiment the average zr in rutile concentration is 4337 32 ppmw zr which is also within the 95 confidence interval of the zr in rutile solubility calibration of ferry and watson contrib mineral petrol 154 429 437 2007 the p t dependencies of ti solubility in quartz and zr solubility in rutile were applied as a thermobarometer to the experimental sample the average ti in quartz isopleth calculated from the calibration of thomas et al contrib mineral petrol 160 743 759 2010 and the average zr in rutile isopleth calculated from the calibration of tomkins et al j metamorph geol 25 703 713 2007 cross at 9 5 kbar and 920 c which is in excellent agreement with the p t conditions of the synthesis experiment separates of the high ti quartz from the initial synthesis experiment described above were used as starting material in subsequent experiments at 20 kbar at which pressure the solubility of ti in quartz is expected to be significantly lower in the recrystallized quartz these recrystallization experiments were conducted under wet and dry conditions at 925 c and under wet conditions at 850 c both wet and dry recrystallization experiments produced polycrystalline quartzites rutile occurs as inclusions in quartz and as individual crystals dispersed along quartz grain boundaries quartz that grew during the recrystallization experiments has dark cathodoluminescence indicating substantially lower ti concentrations the average ti concentrations in quartz from the recrystallization experiments are within the 95 confidence interval of a linear fit to the 20 kbar data of thomas et al contrib mineral petrol 160 743 759 2010 collectively the results from the synthesis and recrystallization experiments confirm that the ti in quartz concentrations used to calibrate the p t dependencies of ti in quartz solubility in thomas et al s contrib mineral petrol 160 743 759 2010 calibration represent the equilibrium concentrations of ti in quartz

a review of lunar chronology revealing a preponderance of 4 34 4 37 ga ages in this study data obtained from sm nd and rb sr isotopic measurements of lunar highlands samples are renormalized to common standard values and then used to define ages with a common isochron regression algorithm the reliability of these ages is evaluated using five criteria that include whether 1 the ages are defined by multiple isotopic systems 2 the data demonstrate limited scatter outside uncertainty 3 initial isotopic compositions are consistent with the petrogenesis of the samples 4 the ages are defined by an isotopic system that is resistant to disturbance by impact metamorphism and 5 the rare earth element abundances determined by isotope dilution of bulk of mineral fractions match those measured by in situ analyses from this analysis it is apparent that the oldest highlands rock ages are some of the least reliable and that there is little support for crustal ages older than 4 40 ga a model age for ur kreep formation calculated using the most reliable mg suite sm nd isotopic systematics in conjunction with sm nd analyses of kreep basalts is 4389 45 ma this age is a good match to the lu hf model age of 4353 37 ma determined using a subset of this sample suite the average modelmore age of 4353 25 ma determined on mare basalts with the 146sm 142nd isotopic system with a peak in pb pb ages observed in lunar zircons of 4340 20 ma and the oldest terrestrial zircon age of 4374 6 ma the preponderance of ages between 4 34 and 4 37 ga reflect either primordial solidification of a lunar magma ocean or a widespread secondary magmatic event on the lunar nearside the first scenario is not consistent with the oldest ages reported for lunar zircons whereas the second scenario does not account for concordance between ages of crustal rocks and mantle reservoirs less

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

rummaging through earth s attic for remains of ancient life abstract we explore the likelihood that early remains of earth mars and venus have been preserved on the moon in high enough concentrations to motivate a search mission during the late heavy bombardment the inner planets experienced frequent large impacts material ejected by these impacts near the escape velocity would have had the potential to land and be preserved on the surface of the moon such ejecta could yield information on the geochemical and biological state of early earth mars and venus to determine whether the moon has preserved enough ejecta to justify a search mission we calculate the amount of terran material incident on the moon over its history by considering the distribution of ejecta launched from the earth by large impacts in addition we make analogous estimates for mars and venus we find for a well mixed regolith that the median surface abundance of terran material is roughly 7 ppm corresponding to a mass of approximately 20 000 kg of terran material over a 10 10 square km area over the same area the amount of material transferred from venus is 1 30 kg and material from mars as much as 180 kg given that the amount of terran material is substantial we estimate the fraction of this material surviving impact with intact geochemical and biological tracers

slope instabilities in dolomieu crater reunion island from seismic signals to rockfall characteristics 1 the seismic signals of hundreds of rockfalls within dolomieu crater piton de la fournaise volcano reunion island have been analyzed to investigate a possible link between physical rockfall generating processes and associated seismic signal features moreover indirect observation of rockfalls via the seismic signals they generate can provide useful data for studying volcanoes and the temporal variations of their structure an increase in the number of rockfall events and their volumes might be an indicator of structural weakness and deformation of the volcano associated with potential eruptive activity the study focuses on a 10 month period following the 6 april 2007 crater floor collapse within dolomieu crater from may 2007 to february 2008 for granular flows a scaling law is revealed between seismic energy and signal duration a semiempirical approach based on both analytical analysis and numerical simulation of these flows shows that a similar scaling law exists between the difference of potential energy computed for an event and its propagation times and also emphasizes the effect of local topography on this scaling law simulated and observed data were compared to evaluate the proportion of potential energy dissipated in the form of seismic waves and confirm a direct link between the seismic energy and potential energy of a given granular flow the mean ratio of seismic to potential energy is of the order of 10 4 comparable to the range of values observed in previous studies a simple method based on these ratios is proposed to estimate the volumes of rockfalls from their seismic signal observed seismic energy and the frequency of rockfalls decreased at the beginning of the studied period and reached a stable level in july thus suggesting a postcollapse relaxation time of dolomieu crater structure of about 2 months from seismic signal analysis which is confirmed by deformation data the total rockfall volume over the study period is estimated to be 1 85 mm3

variation in the indian summer monsoon intensity during the bolling allerod and holocene variations in the indian summer monsoon ism intensity during the last 16 7 ka have been studied using organic carbon corg 15 n of sedimentary organic matter caco3 sediment texture 18 oc and mg ca derived sea surface temperature 18 o of sea water and sea surface salinity in a 14 c dated sediment core from the eastern arabian sea the 18 o in water and planktonic foraminifera shells off the central west coast of india may be controlled by the ism intensity as this area receives high precipitation and land runoff also the corg and caco3 contents of sediments and 15 n of sedimentary organic matter may be linked to ism induced productivity and denitrification the results of the present study reveal that between 16 and 15 2 ka bp the ism was weak with minor fluctuations and started intensifying around 15 2 ka bp at the onset of the bolling allerod b a event the b a event is characterized by higher water column denitrification rates comparable to the present day the ism signatures observed in the 18 oc record of b a event compare well with those from timta cave of the western himalayas and also the asian summer monsoon signatures from the hulu caves in china and warming signatures in greenland ice sheet project 2 gisp2 suggesting atmospheric tele connections through intertropical convergence zone itcz the boundary between the younger dryas and the holocene is discernible with small episodes of abrupt events of increased ism intensity this decrease in 18 oc values at 11 8 ka bp is contemporary with june solar insolation maximum at 30 north and the increase in methane in the gisp2 ice core supporting episodes of warmer climate and increase in ism intensity the ism seems to have been most stable between 7 and 5 6 ka bp the core exhibits periodicity of 500 that is comparable to the atlantic water formation and the chinese monsoon

the 14c dates and 13c 12c ratios of soil organic matter as a means of studying the past vegetation in intertropical regions examples from colombia south america abstract the 14 c ages and 13 c 12 c values were obtained on soil organic matter of various soils sampled in the guasca valley adjacent to the high plain of the sabana de bogota in the colombian cordillera oriental a soil distribution is observed as a function of climatic and altitudinal changes in the lowest parts of the valley planosols are found from the bottom of the valley to 2700 2800 m at altitudes up to 2900 m brunizems and ferrisols occur above 3000 m andic soils are almost everywhere present in more humid mountain zones at present the landscape is widely open without any natural forest nevertheless it was proved by pollen analytical data that at altitudes up to 3000 m the andean forest replaced a paramo formation 13 000 yr ago to conciliate the facts with the known evolution of the vegetal population a first hypothesis consists of admitting that open landscapes were due to a recent anthropogenic destruction of the forest the forest degradation hypothesis was tested by determination of the 13 c 12 c ratio because the trees have a 13 c of 25 to 28 influence of plants with c 3 photosynthesis pathway whereas herbs characteristic of open vegetation such as tropical grasses may have a 13 c of 23 to 16 due to a c 4 photosynthetic cycle the organic matter dated at 13 000 30 000 yr has 13 c close to 25 in the andic soil zone this indicates that at elevations of around 3000 m a cold paramo vegetation was probable for organic matter dated at 12 000 6000 yr 13 c shows a variation from 23 to 21 that does not indicate forest conditions it is uncertain that a forest stage occurred in the past for the planosols brunizem and ferrisol organic matter dated at 13 000 20 000 yr has a 13 c 23 compatible with the paramo vegetational phase occurring at that time for organic matter dated at 9500 yr and less 13 c varies from 20 to 17 these values do not confirm the evidence of forest conditions but rather the existence of open vegetation typified by a mixture of c 3 plants shrubs and rare trees and tropical graminaea thus the 13 c values prove that the valley has known drier and warmer influences that prevented the forest from developing during the holocene to explain the origin of the open landscapes of the valley the hypothesis of recent human deforestation must be discarded moreover the valley appears as a persistent dry enclave in the oriental cordillera

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

kca chronology of lunar granites abstract k ca age determinations were undertaken for three lunar granitic samples 14321 1062 14303 206 and 12013 141 k ca isotopic analyses of bulk samples of seven pristine lunar igneous rocks including four mare basalts 10017 15555 14321 1394 and 14305 304 371 one norite 15445 17 one anorthosite 60025 one kreep basalt 72275 543 and seven meteorites juvinas pasamonte moore county stannern y75011 84b zagami and shergotty were also performed the k ca mineral isochron for lunar granitic clast 14321 1062 yields an age of 4 06 0 07 ga for 40k 0 5543 ga 1 and an initial 40 ca 44 ca of 47 141 0 010 normalized to 42 ca 44 ca 0 31221 the k ca age is in excellent agreement with the rb sr and sm nd ages and is slightly older than the average 39ar 40ar and u pb zircon ages low precision k ca ages of 4 04 0 64 ga and 3 76 0 72 ga were obtained for lunar granites 14303 206 and 12013 141 respectively due to their lower k ca ratios initial 40 ca 44 ca values for seven lunar and seven meteoritic bulk samples are similar and yield an average initial 40 ca 44 ca of 47 136 0 002 2 m and 0 006 2 p assuming this value as the lunar initial 40 ca 44 ca a ten to twenty fold fractionation for k ca during the formation of granite 14321 is calculated for a two stage model the large k ca enrichment is consistent with a granite genesis model involving a silicate liquid immiscibility process literature data for lunar granites studied so far exhibit a wide range of ages from 3 9 to 4 4 ga thus lunar granites probably represent samples from about eight different intrusive bodies the positive k and k ca correlations of lunar rocks strongly supports an early global lunar differentiation however most granites were probably not directly produced from this early differentiation event

raman spectroscopic characterization of h2o in co2 rich fluid inclusions in granulite facies metamorphic rocks abstract water h2o has been identified during raman analyses at 150 200 c of fluid inclusions from granulites that were previously thought to contain pure co2 at room temperature h2o in a co2 rich fluid inclusion forms an optically unresolvable liquid wetting the inclusion walls during heating the h2o phase evaporates into the co2 phase to produce a homogeneous h2o co2 fluid throughout the inclusion volume and the h2o raman peak at 3640 cm 1 is clearly resolvable at elevated temperatures to test and confirm the method synthetic h2o co2 fi of known composition 87 5 mol and 95 mol co2 were also analyzed previously studied granulite samples from the adirondack mountains usa and from the kerala khondalite belt sittampundi complex and sevitturangampatti india were tested for the presence of h2o in co2 rich fluid inclusions traces of h2o were found in co2 rich fluid inclusions in quartz crystals from the adirondacks and from the kerala khondalite belt h2o was not detected in co2 rich secondary fluid inclusions in garnet from the sittampundi complex and from sevitturangampatti rather hydrogarnet was detected along the walls of inclusions in garnet as evidenced by a peak at 3661 cm 1 the hydrogarnet is interpreted to be a step daughter phase that formed by reaction of the h2o in the fluid inclusion with the garnet host during retrogression these observations confirm the presence of an h2o bearing co2 rich fluid at some time during granulite petrogenesis but do not resolve the question of whether these co2 rich fluids were trapped at peak metamorphic conditions or during retrogression or whether the fluid inclusions have reequilibrated following entrapment

stable and radioactive carbon in forest soils of chhattisgarh central india implications for tropical soil carbon dynamics and stable carbon isotope evolution abstract soils from two sites viz kotumsar and tirathgarh located 5 km apart in a tropical reserve forest 18 52 n 81 56 e in central india have been explored for soil organic carbon soc content its mean residence time mrt and the evolution of stable carbon isotopic composition 13c soc stocks in the upper 30 cm of soil layers are 5 3 kg m2 and 3 0 kg m2 in the upper 110 m are 10 7 kg m2 and 7 8 kg m2 at kotumsar and tirathgarh respectively soc decreases with increasing depth bomb carbon signature is observed in the upper 10 cm organic matters in the top soil layers 0 10 cm have mrts of the order of a century which increases gradually with depths reaching 3500 5000 yrs at 100 cm 13c values of soc increase with depth the carbon isotopic fractionation is obtained to be 1 2 and 3 for soils at kotumsar and tirathgarh respectively confirmed using rayleigh isotopic fractionation model the evolution of 13c in soils was also studied using a modified rayleigh fractionation model incorporating a continuous input into the reservoir the depth profiles of 13c for soc show that the input organic matter from surface into the deeper soil layers is either insignificant or highly labile and decomposes quite fast in the top layers thus making little contribution to the residual biomasses of the deeper layers this is an attempt to understand the distillation processes that take place in soc assess the extent of decomposition by microbes and effect of percolation of fresh organic matter into dipper soil layers which are important for stable isotope based paleoclimate and paleovegetation reconstruction and understanding the dynamics of organic carbon in soils

interpreting u pb data from primary and secondary features in lunar zircon in this paper we describe primary and secondary microstructures and textural characteristics found in lunar zircon and discuss the relationships between these features and the zircon u pb isotopic systems and the significance of these features for understanding lunar processes lunar zircons can be classified according to i textural relationships between zircon and surrounding minerals in the host breccias ii the internal microstructures of the zircon grains as identified by optical microscopy cathodoluminescence cl imaging and electron backscattered diffraction ebsd mapping and iii results of in situ ion microprobe analyses of the th u pb isotopic systems primary zircon can occur as part of a cogenetic mineral assemblage lithic clast or as an individual mineral clast and is unzoned or has sector and or oscillatory zoning the age of primary zircon is obtained when multiple ion microprobe analyses across the polished surface of the grain give reproducible and essentially concordant data a secondary set of microstructures superimposed on primary zircon include localised recrystallised domains localised amorphous domains crystal plastic deformation planar deformation features and fractures and are associated with impact processes the first two secondary microstructures often yield internally consistent and close to concordant u pb ages that we interpret as dating impact events others secondary microstructures such as planar deformation features crystal plastic deformation and micro fractures can provide channels for pb diffusion and result in partial resetting of the u pb isotopic systems

revisiting the definitions of the sombric horizon in soil taxonomy and world reference base for soil resources abstract a review of the literature suggests that the sombric horizon from french sombre dark was established in soil taxonomy st and the world reference base for soil resources wrb from limited data and without a clear understanding of how this horizon forms this paper reviews data on sombric horizons evaluates four hypotheses regarding their origin and offers suggestions for improving the identification of sombric horizons of the 30 pedons recognized in the literature as having sombric or sombric like horizons 12 fully satisfied the existing criteria in st and the wrb soils with a true sombric horizon may be restricted to the highlands of central africa burundi rwanda congo on relatively cool mean annual air temperature 16 20 c moist mean annual precipitation 1450 2000 mm plateaus and mountains at elevations ranging from 1450 to 2000 m soils with a sombric horizon occur primarily on highly weathered materials from a variety of crystalline rocks the surface of the sombric horizon occurs at depths of 40 to 110 cm from the surface average 76 cm and ranges from 27 to 100 cm in thickness average 63 cm the sombric horizon commonly is dark reddish brown 5yr 3 3 acidic average ph 4 7 low in exchangeable bases average base saturation 4 high in organic c average 1 3 and despite abundant clay average 56 has a low cation exchange capacity average 12 cmol kg soil based on existing data the sombric horizon contains humus that has migrated downward in the soil possibly in response to climate and vegetation change sombric horizons are not to be confused with sombric like horizons which may contain andic soil properties or spodic materials in soil taxonomy soils with sombric horizons are classified primarily as sombriudoxes 8 pedons and sombrihumults 4 pedons in the world reference base for soil resources sombric horizons occur primarily in umbric ferralsols sombric

40ar 39ar age determinations of lunar basalt meteorites asuka 881757 yamato 793169 miller range 05035 la paz icefield 02205 northwest africa 479 and basaltic breccia elephant moraine 96008 40ar 39ar data are presented for the unbrecciated lunar basaltic meteorites asuka a 881757 yamato y 793169 miller range mil 05035 lapaz icefield lap 02205 northwest africa nwa 479 paired with nwa 032 and basaltic fragmental breccia elephant moraine eet 96008 stepped heating 40ar 39ar analyses of several bulk fragments of related meteorites a 881757 y 793169 and mil 05035 give crystallization ages of 3 763 0 046 ga 3 811 0 098 ga and 3 845 0 014 ga which are comparable with previous age determinations by sm nd u pb th pb pb pb and rb sr methods these three meteorites differ in the degree of secondary 40ar loss with y 793169 showing relatively high ar loss probably during an impact event 200 ma ago lower ar loss in mil 05035 and no loss in a 881757 bulk and impact melt glass bearing samples of lap 02205 gave similar ages 2 985 0 016 ga and 2 874 0 056 ga and are consistent with ages previously determined using other isotope pairs the basaltic portion of eet 96008 gives an age of 2 650 0 086 ga which is considered to be the crystallization age of the basalt in this meteorite the ar release for fragmental basaltic breccia eet 96008 shows evidence of an impact event at 631 20 ma the crystallization age of 2 721 0 040 ga determined for nwa 479 is indistinguishable from the weighted mean age obtained from three samples of nwa 032 supporting the proposal that these meteorites are paired the similarity of 40ar 39ar ages with ages determined by other isotopic systems for multiple meteorites suggests that the k ar isotopic system is robust for meteorites that have experienced a significant shock event and not a prolonged heating regime

seventh foray whitlockite rich lithologies a diopside bearing troctolitic anorthosite ferroan anorthosites and kreep seventeen nonmare samples most of them pristine are characterized and implications of the new data are discussed five pristine samples are from apollo 14 near the center of the kreep rich zone in the moon s western hemisphere three of them are alkali anorthosites rich in ca phosphate whitlockite which apparently crystallized from magmas with ree contents roughly 6 those of high k kreep the alkali anorthosites probably formed from mg rich magmas that assimilated large amounts of urkreep but some might have formed by metasomatism of ferroan anorthosite by urkreep the gabbronorite norite classification scheme is not well suited to western hemisphere lithologies probably due mainly to the overriding effects of longitude petrochemistry correlations a diopside bearing mg rich lithology indicates that a low degree of melting was not a prerequisite for producing gabbroic high ca pyroxene rich mg rich magmas and suggests that some source regions of mg rich magmas were relatively ca rich several pristine kreep fragments from apollo 15 station 2 are texturally and compositionally much like other pristine kreep and thus reinforce the evidence that kreep is highly uniform the pristine anorthosites on the other hand demonstrate further that lunar anorthosites are diverse

seismic recordings of landslides caused by typhoon talas 2011 japan 1 large deep seated landslides occurred in nara wakayama and mie prefectures of western japan when typhoon talas passed through the region on september 3 4 2011 signals of large landslides have been recorded by seismic networks around the world and overall force estimates have been previously determined for large landslides using long period waves this study focuses on the high frequency waveforms and presents signals of 18 landslides caused by typhoon talas 2011 the location of the landslides can be determined by a seismological back projection technique and these locations correlate with the observed surface features we have found that the volumes of the landslide correlated with an energy parameter derived from the seismic records

dynamic velocity and seismic characteristics of gravitational rockfalls at the merapi lava dome abstract gravitational instability of discrete lava lobes in an active dome building volcano may generate rockfalls that travel up to hundreds of meters from the summit understanding the behaviour of rockfalls is important for volcanic hazard assessment as rockfalls can precede large dome collapses that generate pyroclastic flows here we investigate the mechanisms trajectory velocity and seismic characteristic of rockfalls at the merapi volcano through high resolution video and seismic spectrum frequency analysis high resolution videos of rockfall events were converted to images for every second and were scaled with a georeferenced 3d point cloud to convert pixels into scaled units on the order of a meter the scaled images were analysed using pixel tracking to investigate the mechanism trajectory and velocity of rockfalls results illustrate that the rockfall mechanisms include gravitational free fall rolling and bouncing airborne rotation and rolling over high friction basal surfaces the dynamic mechanisms of gravitational rockfalls at merapi are strongly controlled by the topography and the condition of the basal surface which is responsible for the continuous fluctuations in rockfall velocity maximum rockfall velocity occurs when rocks become airborne while rotating over the steepest area with velocity up to 90 m s material rolling over gently sloping high friction basal surfaces can significantly reduce the rockfall velocity to 2 m s which then ceases the rock movement our high resolution video documents the relatively short durations of gravitational rockfall events at merapi in the range of 24 61 s and has different time duration with the short period seismic signals as the movement of small rock fragments over sandy area is not detected by seismic signal spectral analysis of seismic frequencies indicates that gravitational rockfalls at merapi are characterized by high frequencies with a range of 4 17 hz this study provides new insights and improves our understanding of the dynamic mechanism of rockfall events at dome building volcanoes

understanding oblique impacts from experiments observations and modeling natural impacts in which the projectile strikes the target vertically are virtually nonexistent nevertheless our inherent drive to simplify nature often causes us to suppose most impacts are nearly vertical recent theoretical observational and experimental work is improving this situation but even with the current wealth of studies on impact cratering the effect of impact angle on the final crater is not well understood although craters rims may appear circular down to low impact angles the distribution of ejecta around the crater is more sensitive to the angle of impact and currently serves as the best guide to obliquity of impacts experimental studies established that crater dimensions depend only on the vertical component of the impact velocity the shock wave generated by the impact weakens with decreasing impact angle as a result melting and vaporization depend on impact angle however these processes do not seem to depend on the vertical component of the velocity alone finally obliquity influences the fate of the projectile in particular the amount and velocity of ricochet are a strong function of impact angle

tropical rainforest dynamics and palaeoclimate implications since the late pleistocene nilgiris india a multiproxy study involving sedimentology palynology radiocarbon dating stable isotopes and geochemistry was carried out on the parsons valley lake deposit nilgiris india to determine palaeoclimatic fluctuations and their possible impact on vegetation since the late pleistocene the 72 cm deep sediment core that was retrieved reveals five distinct palaeoclimatic phases 1 warm and humid conditions with a high lake stand before the last glacial maximum lgm 29 800 cal yr bp subsequently changing to a relatively cool and dry phase during the lgm 2 considerable dry conditions and lower precipitation occurred between 16 300 and 9500 cal yr bp during this period the vegetation shrank and perhaps was confined to moister pockets or was a riparian forest cover 3 an outbreak in the shift of monsoonal precipitation was witnessed in the beginning of the mid holocene around 8400 cal yr bp implying alteration in the shift toward warm and humid conditions resulting in relatively high pollen abundance for evergreen taxa 4 this phase exhibits a shift to heavier 13 c values around 1850 cal yr bp with an emergence of moist deciduous plants pointing to drier conditions 5 human activities contributed to the exceedingly high percentage of acacia and pinus pollen during the little ice age

paleoclimate and paleovegetation of lower narmada basin gujarat western india inferred from stable carbon and oxygen isotopes abstract surface sediment samples depth 0 160 cm and a paleosol depth 10 15 m both part of a sediment profile exposed in a cliff section of narmada river western india were analyzed for stable isotopes 13 c and 18 o three organic carbon samples from top 160 cm and two paleosol samples from top and bottom of the paleosol were dated by the radiocarbon method 13 c of both soil carbonates and soil organic carbon fall in the range of mixed c3 and c4 vegetation except for the paleosol which shows differences attributable to the contribution of bedrock carbonate during calcite formation the vegetation was dominantly c3 in the late pleistocene from 15 10 ka bp which shifted to mixed c3 c4 during the holocene enhanced monsoon was observed at 12 5 and 1 6 ka bp the presence of c4 grasses in the late holocene is detectable the present day vegetation is dominantly c3 type 13 c 25 4 probably due to anthropogenic activity where grasslands c4 have been replaced by c3 vegetation recently last 50 years the enhanced atmospheric co 2 concentration in recent times could be a probable agent for the current dominance of c3 vegetation

biomass preservation in impact melt ejecta meteorites can have played a role in the delivery of the building blocks of life to earth only if organic compounds are able to survive the high pressures and temperatures of an impact event although experimental impact studies have reported the survival of organic compounds there are uncertainties in scaling experimental conditions to those of a meteorite impact on earth and organic matter has not been found in highly shocked impact materials in a natural setting impact glass linked to the 1 2 km diameter darwin crater in western tasmania is strewn over an area exceeding 400 km2 and is thought to have been ejected by a meteorite impact about 800 kyr ago into terrain consisting of rainforest and swamp here we use pyrolysis gas chromatography mass spectrometry to show that biomarkers representative of plant species in the local ecosystem including cellulose lignin aliphatic biopolymer and protein remnants survived the darwin impact we find that inside the impact glass the organic components are trapped in porous carbon spheres we propose that the organic material was captured within impact melt and preserved when the melt quenched to glass preventing organic decomposition since the impact we suggest that organic material can survive capture and transport in products of extreme impact processing at least for a darwin sized impact event

location of seismic signals associated with microearthquakes and rockfalls on the sechilienne landslide french alps the sechilienne rockslide in the french alps has recently been instrumented with three seismic arrays this network has recorded numerous rockfalls and local microearthquakes because the media is highly fractured it is difficult to identify and pick first arrivals beam forming methods were therefore used to locate these events the method has been adapted to take into account the heterogeneity of seismic wave velocities the location accuracy has been estimated to be about 50 m for epicenters by applying the method to calibration shots depth is less constrained due to uncertainties on the velocity model and due to the seismic network geometry this method of location has then been applied to rockfalls and microearthquakes most rockfalls initiate in the most active part of the rockslide called les ruines the others are located on a recent eroded area aside from les ruines the network also allows the estimation of the rockfall trajectory and propagation speed finally 55 microearthquakes have been located within two zones microearthquakes are located within the first 250 m below the surface most microearthquakes are located in les ruines the most active part of the rockslide where the velocity has increased from 0 5 m yr in 1996 to 1 4 m yr in 2008 these events are located close to three faults that delimit a mass of about 3 6 million m3 other events are located close to the summital scarp in a zone moving at a few centimeters per year the western part of the rockslide which moves more slowly did not produce any event large enough to be detected simultaneously by all stations this seismic monitoring suggests that only a very small fraction of the deformation is released through seismic events

impediments to predicting site response seismic property estimation and modeling simplifications abstract we compare estimates of the empirical transfer function etf to the plane sh wave theoretical transfer function ttf within a laterally constant medium for invasive and noninvasive estimates of the seismic shear wave slownesses at 13 kiban kyoshin network stations throughout japan the difference between the etf and either of the ttfs is substantially larger than the difference between the two ttfs computed from different estimates of the seismic properties we show that the plane sh wave ttf through a laterally homogeneous medium at vertical incidence inadequately models observed amplifications at most sites for both slowness estimates obtained via downhole measurements and the spectral analysis of surface waves strategies to improve the predictions can be separated into two broad categories improving the measurement of soil properties and improving the theory that maps the 1d soil profile onto spectral amplification using an example site where the 1d plane sh wave formulation poorly predicts the etf we find a more satisfactory fit to the etf by modeling the full wavefield and incorporating spatially correlated variability of the seismic properties we conclude that our ability to model the observed site response transfer function is limited largely by the assumptions of the theoretical formulation rather than the uncertainty of the soil property estimates

carbon isotopic composition of lignin biomarkers evidence of grassland over the gangetic plain during lgm abstract carbon isotope 13 c compositions of total organic carbon toc as well as several extracted higher plant derived lignin biomarkers along with the recovery of grass phytoliths provide the first direct evidence of existence of extensive grass land c4 vegetation over the ganges deltaic plain during the last glacial maximum lgm the earliest holocene 9 ka is marked by pronounced 13 c depletion in the lignin phenols coinciding with rapid sea level rise intensified monsoon and replacement of grassland vegetation by mangroves another c4 invasion phase is identified during the late holocene 6 2 ka both the lgm and late holocene c4 phases coincide with the well known monsoon minima the study suggests that change in pco 2 might not be the singular driver of vegetation change as proposed recently and the climate models must take the monsoon like mega climate processes into account for reconstructing the glacial biomes

characterization and analysis of a translational rockslide on a stepped planar slip surface abstract in 2014 a small stepped planar rockslide blocked a road near the town of san germano chisone in northwest italy photographs of the rock cut that failed above the road were taken before and after the rockslide occurred some photos were acquired with the assistance of a uav these photos were used to conduct a forensic analysis of the rockslide with the aid of photogrammetry software it was possible to characterize the slope geometry and the larger geological structures that influenced the slope behaviour a stepped planar slip surface and the shape of the slabs of rock that failed were defined by discontinuities and these were well documented in the 3d photogrammetry models the effective dilation angle was estimated from an assessment of the roughness of the discontinuity surfaces forming the slip surface the stability of the rockslide was analysed as a stepped translational failure mechanism a two block force equilibrium model of the rockslide was developed with this analytic model both deterministic and probabilistic methods were used to study the influence of water pressure as well as time dependent shear strength degradation along the discontinuities and corrosion of rockbolts the analysis suggests that the rockslide was caused by a combination of inadequate rock support time dependent shear strength degradation and water pressure in the joints resulting from above average rainfall

spatial heterogeneity of land cover response to climatic change in the nilgiri highlands southern india since the last glacial maximum fourteen hillslope soil profiles were sampled under natural vegetation i e grassland or forest and plantations in the nilgiri highlands southern india delta 13c ratios were measured at different depths and 14c ages determined for six profiles in these highland soils where the turnover rate of organic matter is extremely low the 13c ratios of entire soil profiles have recorded signatures of past land cover by correlating the data with results previously obtained from peat bogs and with knowledge concerning the history of human settlement we distinguish three contrasting trajectories of palaeoenvironmental history and landscape change since the last glacial maximum in the central nilgiris between 18 and 10 ka bp forest expansion occurred due to the conjunction of a wetter climate the maximum of southwest monsoon related humidity occurring at ca 11 ka bp and higher temperatures since 10 ka bp the reversal towards grassland vegetation is attributed to drier conditions in the western nilgiris where strong southwest monsoon winds permanently restrict forest patches to sheltered valley sites steady but limited expansion of forest from 18 ka bp to the present is recorded and attributed to rising temperatures the southern and eastern nilgiris where the northeast monsoon contributes 20 of the annual rainfall are the less sensitive to fluctuations in the southwest monsoon in these areas rapid and extensive expansion of forest occurred mainly as a consequence of higher temperatures from 18 ka bp to the present massive deforestation by badaga cultivators and europeans planters followed after the 16th century ad as a result and in contrast with the western nilgiris where the land cover mosaic has remained remarkably stable in the last 18 ka bp the current landscape differs sharply from the land cover pattern detected by the soil record

uranium lead ages for lunar zircons evidence for a prolonged period of granophyre formation from 4 32 to 3 88 ga the ages of a number of small fragments of lunar granophyre have been determined by the in situ u th pb isotopic analysis of zircon using a sensitive high mass resolution ion microprobe shrimp i the zircon from lunar granophyre is characterized by consistently high u and th contents most 200 500 ppm and 100 300 ppm respectively compared to zircon from mafic lunar rocks some fragments of lunar granophyre are found to be as old as 4 32 ga supporting other evidence that the original lunar magma ocean crystallized completely within 200 ma of the formation of the moon itself other fragments are as young as 3 88 ga which is much later than the time of formation of most of the lunar crust the older lunar granophyres have rare earth element ree patterns that are similar to lunar kreep whilst the younger granophyres have bow shaped ree patterns that feature a greater relative enrichment in the heavy ree the wide range of ages of numerous lunar zircons lunar granophyres and other rocks indicates that zircon forming magmatism in the lunar highlands was most active prior to 4 3 ga but continuous until at least 3 88 ga the u pb isotopic composition of much lunar zircon is near concordant but the effects of isotopic disturbance as late as 1 0 ga are observed in some zircon both within granophyre fragments recrystallized by reheating and within fragments in which the original delicate silica k feldspar granophyric intergrowth is well preserved it is therefore essential to make multiple analyses of individual zircon grains and preferably analyses of suites of zircons from lunar igneous rocks if they are to be dated reliably by the u pb method it is possible that some of the younger lunar granophyres are the product of large scale silicate liquid immiscibility within late stage differentiates but this remains unproven until remnants of demonstrably cogenetic fe rich immiscible liquid are positively identified

characterization of rockfalls from seismic signal insights from laboratory experiments the seismic signals generated by rockfalls can provide information on their dynamics and location however the lack of field observations makes it difficult to establish clear relationships between the characteristics of the signal and the source in this study scaling laws are derived from analytical impact models to relate the mass and the speed of an individual impactor to the radiated elastic energy and the frequency content of the emitted seismic signal it appears that the radiated elastic energy and frequencies decrease when the impact is viscoelastic or elasto plastic compared to the case of an elastic impact the scaling laws are validated with laboratory experiments of impacts of beads and gravels on smooth thin plates and rough thick blocks regardless of the involved materials the masses and speeds of the impactors are retrieved from seismic measurements within a factor of 3 a quantitative energy budget of the impacts is established on smooth thin plates the lost energy is either radiated in elastic waves or dissipated in viscoelasticity when the impactor is large or small with respect to the plate thickness respectively in contrast on rough thick blocks the elastic energy radiation represents less than 5 of the lost energy most of the energy is lost in plastic deformation or rotation modes of the bead owing to surface roughness finally we estimate the elastic energy radiated during field scale rockfalls experiments this energy is shown to be proportional to the boulder mass in agreement with the theoretical scaling laws

site effects in unstable rock slopes dynamic behavior of the randa instability switzerland we evaluate the dynamic response of the large around five million cubic meters unstable rock slope at randa switzerland based on ground motion recordings during small earthquakes seismic measurements revealed strong polarization of the wavefield in the direction of maximum slope displacement with spectral amplification factors 5 within the unstable area results further highlighted resonant frequencies of both the large unstable rock mass and individual blocks within it block vibration was confirmed by phase analysis of in situ displacement measurements from two bounding tension fractures during a small earthquake numerical simulation using a discontinuous elastic model showed that the presence of steeply dipping compliant fractures is crucial for recreating the observed site response such fractures are common in rock slope instabilities and are here shown to contribute to polarization and amplification of seismic shaking site effects that are rarely considered for hard rock slopes and which may influence the potential for earthquake triggered failure

remote sensing and seismic data integration for the characterization of a rock slide and an artificially triggered rock fall abstract on may 5th 2013 a planar rock slide 450 m3 occurred in the village of la riba ne spain which forced the closure of the road c 240z for 6 months this slide left a hanging block 130 m3 suspended on the slope forcing a controlled blasting followed by rock slope stabilization works the volume of rock displaced during the both events was deduced from lidar and photogrammetry data following two approaches subtracting pre and post event data and reconstructing the volume by fitting planes on the structural surfaces after a structural analysis of the slope information about the natural rock slide was obtained from the records of two permanent broadband seismic stations located 10 km from the site from these seismic records the existence of a rock slide was confirmed and its time of occurrence was determined information that would be otherwise unknown in addition despite the small volume displaced during the event its location was deduced from a single seismic station analysis the blasting process was recorded with two high definition hd video cameras and by two temporary seismic stations deployed close to the site 10 km partially because only a part of the released energy is transmitted into the ground as seismic energy and partially because the recorded seismic signal is highly dependent on the event characteristics and the geotechnical conditions of the ground materials nevertheless seismic data is very well suited to detect and characterize in detail both rockfall events of different nature and size merging and integrating remote sensing techniques such as lidar or photogrammetry with seismic measurements should allow the implementation of rockfall early warning systems

linking holocene drying trends from lonar lake in monsoonal central india to north atlantic cooling events abstract we present the results of biogeochemical and mineralogical analyses on a sediment core that covers the holocene sedimentation history of the climatically sensitive closed saline and alkaline lonar lake in the core monsoon zone in central india we compare our results of c n ratios stable carbon and nitrogen isotopes grain size as well as amino acid derived degradation proxies with climatically sensitive proxies of other records from south asia and the north atlantic region the comparison reveals some more or less contemporaneous climate shifts at lonar lake a general long term climate transition from wet conditions during the early holocene to drier conditions during the late holocene delineating the insolation curve can be reconstructed in addition to the previously identified periods of prolonged drought during 4 6 3 9 and 2 0 0 6 cal ka that have been attributed to temperature changes in the indo pacific warm pool several additional phases of shorter term climate alteration superimposed upon the general climate trend can be identified these correlate with cold phases in the north atlantic region the most pronounced climate deteriorations indicated by our data occurred during 6 2 5 2 4 6 3 9 and 2 0 0 6 cal ka bp the strong dry phase between 4 6 and 3 9 cal ka bp at lonar lake corroborates the hypothesis that severe climate deterioration contributed to the decline of the indus civilisation about 3 9 ka bp

petrology and geochemistry of patuxent range 91501 a clast poor impact melt from the l chondrite parent body and lewis cliff 88663 an l7 chondrite we have performed petrologic and geochemical studies of patuxent range pat 91501 and lewis cliff lew 88663 pat 91501 originally classified as an l7 chondrite is rather a unique near total impact melt from the l chondrite parent body lewis cliff 88663 was originally classified as an achondrite but we find that it is a very weakly shocked l7 chondrite pat 91501 is an unshocked homogeneous igneous textured ultramafic rock composed of euhedral to subhedral olivine low ca pyroxene augite and chrome rich spinels with interstitial albitic plagioclase and minor silica alumina alkali rich glass only 10 relic chondritic material is present olivine grains are homogeneous fa25 2 26 8 low ca pyroxene wo1 9 7 2en71 9 78 2fs19 9 20 9 and augite wo29 8 39 0en49 2 55 3fs11 8 14 9 display a strong linear tio2 al2o3 correlation resulting from igneous fractionation plagioclase is variable in composition or3 0 7 7ab79 8 84 1an8 2 17 2 chrome rich spinels are variable in composition and zoned from cr rich cores to ti al rich rims some have evolved compositions with up to 7 9 wt tio2 pat 91501 bulk silicate has an l chondrite lithophile element composition except for depletions in zn and br siderophile and chalcophile elements are highly depleted due to sequestration in centimeter size metal troilite nodules the minerals in lew 88663 are more uniform in composition than those in pat 91501 olivine grains have low cao and cr2o3 contents similar to those in l5 6 chondrites pyroxenes have high tio2 contents with only a diffuse tio2 al2o3 correlation low ca pyroxenes are less calcic wo1 6 3 1en76 5 77 0fs20 4 21 4 while augites wo39 5 45 6en46 8 51 1fs7 6 9 4 and plagioclases or2 6 5 7ab74 1 83 1an11 2 23 3 are more calcic spinels are homogeneous and compositionally similar to those in l6 chondrites lew 88663 has an l chondrite bulk composition for lithophile elements and only slight depletions in siderophile and chalcophile elements that are plausibly due to weathering and or sample heterogeneity