long range earthquake forecasting with every earthquake a precursor according to scale scaling relations previously derived from examples of the precursory scale increase before major earthquakes show that the precursor is a long term predictor of the time magnitude and location of the major earthquake these relations are here taken as the basis of a stochastic forecasting model in which every earthquake is regarded as a precursor the problem of identifying those earthquakes that are actually precursory is thus set aside at the cost of limiting the strength of the resulting forecast the contribution of an individual earthquake to the future distribution of hazard in time magnitude and location is on a scale determined through the scaling relations by its magnitude provision is made for a contribution to be affected by other earthquakes close in time and location e g an aftershock may be given low weight using the new zealand catalogue the model has been fitted to the forecasting of shallow earthquakes exceeding magnitude 5 75 over the period 1965 2000 it fits the data much better than a baseline poisson model with a location distribution based on proximity to the epicenters of past earthquakes further the model has been applied with unchanged parameters to the california region over the period 1975 2001 there also it performs much better than the baseline model fitted to the same region over the period 1951 1974 the likelihood ratio is 1015 in favor of the present model these results lend credence to the precursory scale increase phenomenon and show that the scaling relations are pervasive in earthquake catalogues the forecasting model provides a new baseline model against which future refinements and other proposed models can be tested it may also prove to be useful in practice its applicability to other regions has still to be established

fingerprinting the water site in mantle olivine nominally anhydrous minerals such as olivine contain trace amounts of water and may accommodate the entire water budget of the upper mantle here we report for the first time synthetic olivines crystallized experimentally under upper mantle conditions that reproduce the most common and intense infrared hydroxyl stretching bands at 3572 and 3525 cm 1 observed in spinel peridotite mantle olivines these bands arise from water accommodated at point defects associated with the trace element ti and we suggest that this is the most important defect site in the shallow upper mantle additional hydrated defects may occur at higher pressures we also identify bands related to water associated with fe3 these are unlikely to reflect equilibrium with the mantle and indicate water incorporation during exhumation or retrogression water must be present at the defect site appropriate for the mantle at the conditions of interest for partitioning seismic wave speed and deformation experiments on hydrous olivine to be relevant

birth death and resurrection the life cycle of suprasubduction zone ophiolites 1 suprasubduction zone ssz ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites this sequence includes the following 1 birth which entails the formation of the ophiolite above a nascent or reconfigured subduction zone this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex 2 youth during which is continued melting of refractory asthenosphere depleted during birth occurs in response to fluid flux from the subducting slab with extensional deformation of the older plutonic suite eruption of refractory lavas and the intrusion of wehrlite pyroxenite 3 maturity with the onset of semistable arc volcanism typically calc alkaline as the subduction zone matures and stabilizes and the intrusion of quartz diorite and eruption of silicic lavas and 4 death which is the sudden demise of active spreading and ophiolite related volcanism which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites 5 resurrection with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction the early stages 1 3 may be diachronous and each stage may overlap in both time and space the existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the ssz tectonic setting

estimation of deformation temperatures flow stresses and strain rates from an intra continental shear zone the main boundary thrust nw himalaya uttarakhand india abstract this work generates thermal and tectonic data from the mylonitized rocks of the main boundary thrust mbt south and north to this major thrust the siwalik range and the lesser himalaya respectively have been receiving a renewed interest amongst the petroleum geoscientists understanding temperature flow stress and strain rates related to a major thrust is crucial in thermal mechanical modelling of the terrains adjacent to it strongly sheared proterozoic chandpur phyllites and abundant syntectonic quartz veins occur along the mbt zone one of the major foreland verging thrusts in the himalayan orogen near the sahenshahi temple at dehradun uttarakhand state india microstructure analyses show intense ductile top to s shear in terms of s c fabric and xrd analyses indicate presence of clays e g illite and clinochlore these clays not only bear the signatures of the intense fluid activity but also enhance the fault movement by reducing the mechanical strength of the fault zone rocks thermometry based on qualitative quartz grain boundary mobility 300 550 c and quantitative laser raman spectroscopy for carbonaceous materials 340 370 c reveal the maximum estimates of the deformation temperature and metamorphic temperature respectively the higher temperature microstructures can be found in lower temperature domains under the presence of fluids hence the quartz thermometry estimates a broader temperature range than the raman thermometry previous works report that the phyllites present at the base of a thrust sheet experiences deformation at

paleomagnetism of jurassic radiolarian chert above the coast range ophiolite at stanley mountain california and implications for its paleogeographic origins upper jurassic red tuffaceous chert above the coast range ophiolite at stanley mountain california lat 35 n long 240 e contains three components of remanent magnetization the first component a removed by 100 200 c has a direction near the present day field for southern california and is probably a recently acquired thermoviscous magnetization a second component b removed between 100 and 600 c is identical to that observed by previous workers in samples of underlying pillow basalt and overlying terrigenous sedimentary rocks this component has constant normal polarity and direction throughout the entire section although these rocks were deposited during a mixed polarity interval of the geomagnetic field the b magnetization therefore is inferred to be a secondary magnetization acquired during accretion uplift or miocene volcanism prior to regional clockwise rotation the highest temperature component c removed between 480 and 680 c is of dual polarity and is tentatively interpreted as a primary magnetization although it fails a reversal test possibly due to contamination by b separation of the b and c components is best shown by samples with negative inclination c directions and a corrected mean direction using only these samples indicates an initial paleolatitude of 32 n 8 paleobiogeographic models relating radiolarian faunal distribution patterns to paleolatitude have apparently been incorrectly calibrated using the overprint b component few other paleomagnetic data have been incorporated in these models and faunal distribution patterns are poorly known and mostly unquantified the available data therefore do not support formation of the coast range ophiolite at stanley mountain near the paleoequator or accretion at 10 n paleolatitude as has been previously suggested based on paleomagnetic data but indicate deposition near expected paleolatitudes for north america 35 n 4 during late jurassic time

sr isotopic tracer study of the samail ophiolite oman we have measured rb and sr concentrations and sr isotopic compositions in 41 whole rock samples and 12 mineral separates from units of the samail ophiolite including peridotite gabbro plagiogranite diabase dikes and gabbro and websterite dikes within the metamorphic peridotite ten samples of cumulate gabbro from the wadir kadir section and nine samples from the wadi khafifah section have mean 87sr 86sr ratios and standard deviations of 0 70314 0 00030 and 0 70306 0 00034 respectively the dispersion in sr isotopic composition may reflect real heterogeneities in the magma source region the average sr isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern midocean ridge basalt the 87sr 86sr ratios of noncumulate gabbro plagiogranite and diabase dikes range from 0 7034 to 0 7047 0 7038 to 0 7046 and 0 7037 to 0 7061 respectively these higher 87sr 86sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with seawater mineral separates from dikes that cut harzburgite tectonite have sr isotopic compositions which agree with that of cumulate gabbro these data indicate that the cumulate gabbro and the different dikes were derived from partial melting of source regions that had similar long term histories and chemical compositions

evaluation of kimberlite diamond potential using ftir spectroscopy of xenocrystic olivine abstract xenocrysts or phenocrysts of olivine in kimberlite show a diversity of hydroxyl related infrared absorption bands that reflect compositional variation of their mantle source and conditions of last equilibration interpretation of infrared spectra of olivine in terms of equilibration crystallization conditions may help to isolate spectral features associated with good diamond carrying and diamond preservation potential as an exploratory study we examine by ftir the spectroscopic features of olivine inclusions in diamond olivine coexisting with diamond in peridotite xenoliths and olivine from diamond free peridotite xenoliths the three environments are respectively characterized by spectroscopically anhydrous olivine olivine with low water concentrations h 2 o 2 o up to 260 ppm previous studies have shown that the majority of olivine macrocrysts in kimberlite contain 100 ppm h 2 o with a significant proportion containing 250 ppm h 2 o our new results suggest that hydrogenation of olivine occurs in the mantle during equilibration with kimberlite related hydrous fluids and or during equilibration with or crystallization from kimberlite magmas during ascent the association of gem diamonds with water poor mantle olivine suggests that such samples experienced limited interaction with hydrous fluids melts over a short time span thus preventing diffusional equilibration future ftir studies of olivine from kimberlites with widely variable diamond grades and reconciliation with diamond resorption features may permit development of new ftir based procedures to assist in the evaluation of new kimberlite discoveries

new ages for the post howiesons poort late and final middle stone age at sibudu south africa abstract optically stimulated luminescence osl measurements are reported for single grains of quartz from deposits within sibudu rock shelter such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates three types of single grain equivalent dose de distributions were observed one sample represented a single dose population three samples indicated mixing between iron age ia and middle stone age msa deposits and 10 samples in addition to the three mixed samples showed scattered distributions the latter type resulted from differences in the beta dose received by individual grains for these samples the beta doses were modelled and adjusted accordingly ages for the 14 samples collected from msa deposits post dating the howiesons poort hp resulted in three age clusters which are stratigraphically consistent with the three informally named cultural phases at sibudu namely the post hp late msa and final msa weighted mean ages of 58 5 1 4 ka 47 7 1 4 ka and 38 6 1 9 ka were calculated for these phases respectively the three phases were separated by two occupational hiatuses with durations of 10 8 1 3 ka and 9 1 3 6 ka we hypothesise that the punctuated presence of humans at sibudu was determined by large scale fluctuations in climate during oxygen isotope stage ois 3 which resulted in alternating wet and dry periods phases of occupation correspond to wet periods when fresh water was available in the tongati river whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water where people migrated to remains unresolved

fossil bird study and paleoecological and paleoenvironmental consequences example from the saint gerand le puy deposits lower miocene allier france abstract study of the aquatic avifauna from the agenian deposits of the saint gerand le puy area allier department france proves that paleornithology is not only a systematical and evolutionary science but also that it can provide interesting data sometimes unsuspected from the study of other animal groups on paleoecological paleoenvironmental and paleoclimatological conditions thus the comparison of the ecological adaptations of such fossil species from this area with those of their nearest living relatives provides new information about the paleoenvironment such as climatic and physico chemical conditions water depth predation relationships and migration

petrology and origin of primitive lavas from the troodos ophiolite cyprus parental magmas to the troodos ophiolite are characterised by low tio2 and al2o3 and high sio2 extremely fresh and chemically primitive high mgo rocks are found within the upper pillow lavas and along the arakapas fault belt of cyprus and contain forsteritic olivine enstatite and groundmass clinopyroxene set in glass or plagioclase with accessory magnesiochromite and sometimes hornblende they are quartz normative and may have originally contained up to 3 wt h2o geochemically there are three distinct groups of primitive lavas based on tio2 and zr contents but also reflected by cao na2o and ree abundances these groups cannot be related by crystal fractionation and are considered to have been generated by incremental melting of a variably depleted source region the parental magma to the least depleted group group i was that of the major portion of the troodos plutonic complex and is similar to those postulated for other low ti ophiolites chemically it has close affinities with komatiitic basalts the most depleted lavas group iii all have u shaped ree profiles and variable 143nd 144nd ratios interpreted in terms of metasomatism of the source region by an incompatible element enriched component which was probably derived from a subducted slab these lavas represent an intermediate step in the development of boninite series rocks

demarcation and scaling of long term seismogenesis a space time envelope of minor seismicity related to major shallow earthquakes is identified from observations of the long term precursory scale increase phenomenon which quantifies the three stage faulting model of seismogenesis the envelope which includes the source area of the major earthquake is here demarcated for 47 earthquakes from four regions with tectonic regimes ranging from subduction to continental collision and continental transform the earthquakes range in magnitude from 5 8 to 8 2 and include the 24 most recent mainshocks of magnitude 6 4 and larger in the san andreas system of california the hellenic arc region of greece and the new zealand region together with the six most recent mainshocks of magnitude 7 4 and larger in the pacific arc region of japan also included are the destructive earthquakes that occurred at kobe japan 1995 magnitude 7 2 izmit turkey 1999 magnitude 7 4 and w tottori japan 2000 magnitude 7 3 the space a p in the space time envelope is optimised with respect to the scale increase while the time t p is the interval between the onset of the scale increase and the occurrence of the earthquake a strong correlation is found between the envelope a p t p and the magnitude of the earthquake hence the conclusion that the set of precursory earthquakes contained in the envelope is intrinsic to the seismogenic process yet a p and t p are correlated only weakly with each other suggesting that a p is affected by differences in statical conditions such as geological structure and lithology and t p by differences in dynamical conditions such as plate velocity among other scaling relations predictive regressions are found between on the one hand the magnitude level of the precursory seismicity and on the other hand both t p and the major earthquake magnitude hence the method as here applied to retrospective analysis is potentially adaptable to long range forecasting of the place time and magnitude of major earthquakes

using synthetic seismicity to evaluate seismic hazard in the wellington region new zealand summary a computer synthetic seismicity program for the wellington region has been implemented and used to infer the effect of the 1848 awatere and 1855 wairarapa mega earthquakes on the timing of the next characteristic magnitude 7 35 or more earthquake on the wellington hutt valley section of the wellington fault we find that on average over several hundred cases a wellington fault event is delayed by 259 years the synthetic catalogue of 500 000 events magnitude 5 5 or more also gives the average recurrence time of characteristic wellington fault events 960 yr and their coefficient of variation 0 40 there is also a strong retarding effect on moderate magnitude wellington fault events magnitude 6 5 7 3 sensitivity tests indicate that these results are robust the synthetic model contains 58 known major faults and 3000 randomly placed small faults to reproduce the rate and spatial distribution of background seismicity observed recently from the synthetic catalogue it is possible to determine the average recurrence rate for all major faults also there is strong evidence of the short term 10 yr temporal clustering of large events throughout the region a factor that contributes to a highly variable moment release rate over time spans of a few hundred years

long range earthquake forecasting allowing for aftershocks summary an earthquake occurrence model aimed at forecasting main shocks can be adjusted to allow for the occurrence of aftershocks conforming to well known empirical relations describing their temporal decay magnitude distribution and spatial extent modifications are proposed to the every earthquake a precursor according to scale eepas long range forecasting model to allow for the occurrence of aftershocks of predicted events using earthquake catalogues of california and the kanto region central japan versions of the modified and original eepas model are fitted to a period of about 10 yr and independently tested on a later period of about 10 yr of each catalogue for the testing period the increase in the log likelihood per earthquake of the modified models over their original counterparts is about 0 1 on average this gives preliminary confirmation of the efficacy of the modifications versions of the modified model will be submitted to regional testing centres of the collaboratory for the study of earthquake predictability for further independent performance testing in real time

the challenges of probabilistic seismic hazard assessment in stable continental interiors an australian example in stable continental regions scrs the process of probabilistic seismic hazard assessment psha remains a scientific and technical challenge in producing a new national hazard model for australia we developed several innovative techniques to address these challenges the australian seismic catalog is heterogeneous due to the variability between magnitude types and the sparse networks to reduce the resulting high epistemic uncertainty in the recurrence parameters a and b the magnitudes of pre 1990 earthquakes have been empirically corrected to account for changes in magnitude formulas around 1990 in addition existing methods for estimating recurrence parameters e g maximum likelihood estimation were found to be unstable to overcome this problem a new method was developed that removes outlier earthquakes before applying a regression the incorporation of a model of episodic seismicity into the new hazard model required deviation from the more conventional method of psha the selection of the maximum earthquake magnitude m max is based on the analysis of surface ruptures from paleoearthquakes with m max thought to vary between geological domains e g 7 2 7 6 in nonextended scr and 7 4 7 8 in extended scr the sensitivity of psha to m max source zone boundary location recurrence parameters and ground motion prediction equations gmpes was examined in this study the hazard was found to be generally insensitive to m max in the estimated preferred magnitude range the uncertainty in recurrence parameters was found to contribute a variation in hazard comparable to the epistemic uncertainty associated with the different gmpes used in this study for sites near source zone boundaries a similar variation in hazard was observed by reasonable changes in the position of the boundaries aleatory variability and epistemic uncertainty in gmpes are routinely incorporated in pshas as is variation in m max however the uncertainties in recurrence parameters and source zone boundaries are generally given less attention

late quaternary dynamics of southern africa s winter rainfall zone abstract variations in the nature and extent of southern africa s winter rainfall zone wrz have the potential to provide important information concerning the nature of long term climate change at both regional and hemispheric scales positioned at the interface between tropical and temperate systems southern africa s climate is influenced by shifts in the intertropical convergence zone the westerlies and the development and position of continental and oceanic anticyclones over the last glacial interglacial cycle substantial changes in the amount and seasonality of precipitation across the subcontinent have been linked to the relative dominance of these systems central to this discussion has been the extent to which the region s glacial climates would have been affected by expansions of antarctic sea ice equatorward migrations of the westerlies more frequent intense winter storms and an expanded wrz this paper reviews the developing body of evidence pertaining to shifts in the wrz and the evolution of ideas that have been presented to explain the patterns observed dividing the region into three separate axes along the western and southern margins of the continent and across the interior into the karoo and the kalahari a range of evidence from both terrestrial sites and marine cores is considered and potential expansions of the wrz expansions are explored despite the limitations of many of the region s proxy records a coherent pattern has begun to develop of a significantly expanded wrz during phases of the last glacial period with the best documented being between 32 17 ka while more detailed inferences will require the recovery and analysis of longer and better dated records this synthesis provides a new baseline for further research in this key region

probable evidences of bone accumulation by pleistocene bearded vulture at the archaeological site of el miron cave spain the bearded vulture gypaetus barbatus a bird or prey that mainly feeds on bones of large mammal carcasses has been recently evidenced as an accumulating agent with significant contributions to palaeontological assemblages in caves and shelters but extremely rare at archaeological sites the results of the taphonomic analyses carried out in the upper palaeolithic layers of el miron cave cantabrian spain which are presented here evidence the existence of special digestive marks and a typical skeletal pattern in a noticeable amount of small and medium sized ungulates bones this fact suggest that a representative part of the bone assemblage has been caused by bearded vultures and strengthens the idea that this bird has to be definitely included among other potential non human accumulators in archaeological sites

cryptic mineral chemistry variations in a detailed traverse through the cumulate ultramafic rocks of the north arm mountain massif of the bay of islands ophiolite newfoundland

differential burning recrystallization and fragmentation of archaeological bone abstract this paper presents research on the conditions under which progressive levels of burning may occur to archaeological bone and how burning damage changes bones crystal structure and susceptibility to fragmentation a k a friability experiments were conducted to simulate common patterns of high temperature bone diagenesis and fragmentation previously documented in paleolithic shelter sites bones buried up to 6 cm below the coal beds of the experimental fires were carbonized but calcination occurred only with direct exposure to live coals analysis by infra red spectroscopy reveals that marked changes in crystallinity accompany the macroscopic transformations in colour and friability of modern fire altered bone specifically a monotonic non linear decrease in mean fragment length across six colour categories was observed when samples were agitated or trampled and a concordant decline in bone identifiability first with respect to skeletal element and ultimately the recognizability of bone tissue itself these findings help qualify the behavioural and taphonomic implications of fragmented burned bones in archaeological sites especially with regard to potential stratigraphic associations between artefacts and hearth features in sites and the intensity of space use by human occupants the identification of burning damage on archaeological bone is a separate issue however it was found that the molecular signatures of recrystallization in modern burned bones partly overlap with recrystallization caused by weathering after only 1 to 2 years of exposure in an arid setting and by partial fossilization of archaeological bones over the long term while infra red and x ray diffraction techniques effectively describe heat induced changes in modern bone mineral and are an important aid for modelling diagenetic processes these techniques did not reliably identify burning damage to archaeological bones cross referencing readily visible colour phases with hcl insoluble fraction data proves much more effective and economically feasible for the latter purpose

late pleistocene stalagmite growth in wolkberg cave south africa little is known about the sequence of climate and environmental change in southern africa during the last glacial period in spite of the intimations from records such as antarctic ice cores and archaeological sites that very marked changes took place which would have had profound effects on vegetation and animal distributions across the sub continent high resolution semi continuous climate and environmental records can be extracted from suitable cave speleothems speleothems are reasonably abundant in southern africa but their occurrence is patchy in time and space and the records can be difficult to interpret here we report our assessment of the stalagmite w5 from wolkberg cave in the northeastern part of south africa as an archive for glacial period climatic and environmental shifts the cave is located at 1450 m asl in the dolomitic limestones of the transvaal system in an area currently dominated by c4 grass vegetation nine u th dates show growth from 58 to 46 ka and a second brief phase ca 40 ka indicating that the available moisture was sufficient to allow speleothems to form the 18o and 13c values along the growth axis show variability in the order of 2 for the former while variability in the latter is characterized by a shift from values near 2 in the older section to 2 or more in the younger part these high 13c values are probably the combined result of co2 degassing of the percolating soil water prior to the carbonate precipitation in the cave chamber the increasing dominance of c4 over c3 vegetation and the high percentage of aragonite towards the stalagmite s top the retrieved data point towards increasingly drier and colder conditions during the growth period of the stalagmite furthermore the high frequency variations of 18o values indicate the presence of short term climate oscillations that are probably linked to shifts of the intertropical convergence zone

melting experiments on the udachnaya kimberlite at 6 3 7 5 gpa implications for the role of h2o in magma generation and formation of hydrous olivine abstract melting experiments on kimberlite from the udachnaya pipe have been performed at 6 3 7 5 gpa and 1300 1600 c using a split sphere multianvil apparatus the water content in kimberlite varied from 2 5 to 11 6 wt and the co 2 co 2 h 2 o molar ratio was from 0 61 to 0 23 the samples were placed in a graphite container inside a pt capsule the oxygen fugacity f o 2 during the experiment was controlled by the equilibrium between graphite and water bearing carbonate silicate melt at relatively low temperatures f o 2 was close to the emog d equilibrium at higher temperatures it shifted for approximately 1 log unit to more reduced conditions an olivine garnet clinopyroxene assemblage was present at 100 c below the liquidus of the udachnaya kimberlite with 6 8 wt h 2 o at the pressure 6 3 gpa and 6 10 wt h 2 o at 7 5 gpa at 2 5 wt h 2 o the same assemblage appeared at 150 c below liquidus both at 6 3 and 7 5 gpa orthopyroxene did not form at any temperature and pressure of the experiments the presence of clinopyroxene near the liquidus was due to the calcic nature and a high degree of silica undersaturation in the udachnaya kimberlite at the supra solidus conditions garnet and clinopyroxene compositionally distinct from minerals of the megacryst macrocryst suite crystallized in equilibrium with low h 2 o carbonated melt near the liquidus of high h 2 o kimberlite the stable olivine composition was from fo 91 to fo 98 the garnet composition cao 8 wt tio 2 2 o 3 up to 2 2 wt approached that of ti bearing garnet typical of cr poor garnet megacrysts while the clinopyroxene was an analog of clinopyroxene megacrysts in kimberlite infrared absorption measurements showed that crystallized olivines contained water in the form of ti clinohumite like and oh clinohumite like defects the h 2 o content of olivine was found to depend mainly on water content in kimberlite melt and pressure olivine with 120 170 ppm h 2 o crystallized at 6 gpa in equilibrium with the melt compositionally close to the archetypical kimberlite rather than a carbonate one and water as high as 6 wt olivine with 270 300 ppm h 2 o crystallized near kimberlite liquidus only at 7 5 gpa and 9 5 10 1 wt h 2 o the experimental results imply that hydrous olivine which is typical to kimberlites including the udachnaya pipe very unlikely can crystallize from anhydrous carbonated magma judging by the conditions for multiphase saturation of the udachnaya kimberlite melt its generation was possible by partial melting of carbonated garnet wehrlite at pressures from 6 to 7 5 gpa and temperatures within 1450 1600 c in the presence of aqueous fluids thus water must have been a trigger for generation of the primary kimberlite magma

the eepas forecasting model and the probability of moderate to large earthquakes in central japan abstract the eepas every earthquake a precursor according to scale model is a space time point process model based on the precursory scale increase phenomenon and associated predictive scaling relations it has previously been fitted to the new zealand earthquake catalogue and applied successfully in quasi prospective tests on the cnss catalogue for california for forecasting earthquakes with magnitudes above 5 75 and on the jma catalogue of japan for magnitudes above 6 75 here we test whether the scaling relations extend to lower magnitudes by applying eepas to depth restricted subsets of the nied catalogue of the kanto area central japan for magnitudes above 4 75 as in previous studies the eepas model is found to be more informative than a quasi static baseline model based on proximity to past earthquakes and much more informative than the stationary uniform poisson model the information that it provides is illustrated by maps of the earthquake occurrence rate density covering magnitudes from 5 0 to 8 0 for the central japan region as at the beginning of year 2004 using the nied and jma catalogues to mid 2003

the origin of high hydrogen content in kimberlitic olivine evidence from hydroxyl zonation in olivine from kimberlites and mantle xenoliths abstract olivine macrocrysts in kimberlites are the most h rich natural olivines known their xenocrystic provenance makes unclear whether h enrichment occurred in the mantle prior to entrainment in kimberlite magma or during ascent we present a fourier transform infrared ftir spectroscopy based study of h zonation in kimberlite derived olivine macrocrysts and or olivine in xenoliths from the kimberlites jericho nunavut canada beartooth northwest territories canada and pipe 200 and matsoku lesotho the objective of the study was to determine whether changes in the concentration or speciation of h defects in proximity to the host kimberlite could yield insights into the origin of h enrichment within the group 1 region of the ftir spectrum 3420 3700 cm 1 we find that olivines within xenoliths and macrocrysts show weak zonation or significant h depletions in rims peaks in the group 2 region 3260 3420 cm 1 in beartooth olivines show marked decrease in the crystal margins in comparison to group 1 peaks we find no preserved evidence for kimberlite related h enrichment in our dataset we ascribe h depletion to diffusive h loss to infiltrating kimberlitic media diffusion models using coefficients previously applied to dehydrogenation of olivine and assuming a dry environment produce extremely short ascent durations incompatible with the results of other geospeedometers this mismatch suggests that the poorly developed zonation in jericho and beartooth olivines indicates water enrichment and or faster ascent of these melts in comparison to pipe 200 and matsoku resulting in greater retention of mantle derived h a further significant factor in the mismatch is the differing speciation of h in most natural mantle derived olivines in comparison to those used in diffusion experiments we argue that the presence of presumably mantle derived group 2 h in olivine macrocrysts indicates rapid ascent of magma exsolving water rich fluid permitting preservation of these faster diffusing defects only in particularly rapidly ascending kimberlite magmas this interpretation explains empirical correlations between the presence of group 2 bands water derived diamond resorption features and volcaniclastic kimberlite facies

middle stone age bone tools from the howiesons poort layers sibudu cave south africa abstract recently discovered bone implements from middle stone age msa deposits at sibudu cave south africa confirm the existence of a bone tool industry for the howiesons poort hp technocomplex previously an isolated bone point from klasies river provided inconclusive evidence this paper describes three bone tools two points and the end of a polished spatula shaped piece from unequivocal hp layers at sibudu cave with ages greater than 61 ka comparative microscopic and morphometric analysis of the sibudu specimens together with bone tools from southern african middle and later stone age lsa deposits an iron age occupation nineteenth century bushman hunter gatherer toolkits and bone tools used experimentally in a variety of tasks reveals that the sibudu polished piece has use wear reminiscent of that on bones experimentally used to work animal hides a slender point is consistent with a pin or needle like implement while a larger point reminiscent of the single specimen from peers cave parallels large un poisoned bone arrow points from lsa iron age and historical bushman sites additional support for the sibudu point having served as an arrow tip comes from backed lithics in the hp compatible with this use and the recovery of older larger bone and lithic points from blombos cave interpreted as spear heads if the bone point from the hp layers at sibudu cave is substantiated by future discoveries this will push back the origin of bow and bone arrow technology by at least 20 000 years and corroborate arguments in favour of the hypothesis that crucial technological innovations took place during the msa in africa

complex characteristics of slow slip events in subduction zones reproduced in multi cycle simulations 1 since the discovery of slow slip events along subduction zone interfaces worldwide dense geodetic and seismic networks have illuminated detailed characteristics of these events and associated tremor high resolution observations of tremor where the spatial temporal evolution is presumed to reflect that of the underlying slow slip events show highly complex patterns in which the origins remain poorly understood we present a new computationally efficient modeling technique that reproduces many features of observed slow slip events including slow initiation coalescence of separate events and rapid back propagation of renewed slip over previously slipped regions rapid back propagation speeds are explained as a consequence of rate and state dependent frictional healing consistent with analytical solutions developed in support of the simulations

geochemistry and intrusive directions in sheeted dikes in the troodos ophiolite implications for mid ocean ridge spreading centers 1 sheeted dikes at mid ocean ridge volcanoes represent the link between deep magma production and storage processes and shallow processes such as volcanism and hydrothermal activity as such they are crucial for the interpretation of many observations at mid ocean ridges or other volcanoes with pronounced rift zones including topography hydrothermal systems petrology and geochemistry we carried out a structural magnetic and chemical investigation of a 4 10 km sheeted dike section in the troodos ophiolite cyprus on the basis of major and trace element geochemistry we distinguish dikes that may be correlated with the basal high ti series hts lavas from those of the overlying low ti series lts lavas all dikes studied are nearly parallel to each other with vertical or steeply dipping planes whose strike likely indicates the orientation of the spreading center anisotropy of magnetic susceptibility measurements suggests that the hts and lts dikes intrude in fundamentally different ways hts dikes reflect the intrusive behavior of dikes in the vicinity of a magma supply system and define ridge parallel intrusive sheets that radiate out from the magma chamber lts dikes show a bimodal orthogonal set of intrusive directions one shallow and one near vertical near lateral propagating dikes provide a means for delivery of magma into distant portions of a rift system and near vertical dike propagation directions are probably associated with feeder dikes to down rift surface flows our study suggests that the types of dike intrusive behavior in the troodos ophiolite may also be typical for normal mid ocean ridges or other major shield volcanoes with well developed rift zones

multi event simulations of slow slip events for a cascadia like subduction zone 1 we employ the earthquake simulator rsqsim which incorporates rate and state dependent friction to investigate characteristics of slow slip events sses along a cascadia like mega thrust the simulations consist of 100 000 sses with equivalent moment magnitudes mw4 0 7 0 the largest simulated sses mw6 4 7 0 have inter event times of 19 months durations of 10 40 days mean slips of 2 2 4 1 cm and along strike propagation speeds of 7 20 km day which are comparable to observations from cascadia the simulations show quiescence after mw 6 4 sses followed by a progressive increase in both the magnitude and frequency of sses prior to the next large event small sses below mw5 6 develop in an incoherent manner and have irregular geometries while larger sses show highly coherent growth of the slip region and spontaneous but transient event to event segmentation the change in event characteristics at mw5 6 corresponds to a break in the scaling of seismic moment with slip fault area and duration

comparative performance of time invariant long range and short range forecasting models on the earthquake catalogue of greece 1 time invariant long range and short range forecasting models were fitted to the earthquake catalogue of greece for magnitudes 4 0 and greater to optimize their ability to forecast events of magnitude 6 0 and greater in the period 1966 1980 the models considered were stationary spatially uniform and spatially varying poisson models a long range forecasting model based on the precursory scale increase phenomenon with every earthquake regarded as a precursor according to scale and epidemic type short range forecasting models with spatially uniform and spatially varying spontaneous seismicity each of the models was then applied to the catalogue for 1981 2002 and their forecasting performance was compared using the log likelihood statistic the long range forecasting model performed substantially better than the time invariant models and the short range forecasting models performed substantially better again the results show that the information value to be gained from modeling temporal and spatial variation of earthquake occurrence rate at both long and short range is much greater than can be gained from modeling spatial variation alone

hydroxyl in olivines from mantle xenoliths in kimberlites of the siberian platform from a total of 335 olivine crystal grains crystallographically orientated platelets and where possible parallelepipeds were prepared chemically analysed by electron microprobe examined under the polarisation microscope and studied by polarised ftir microscope absorption spectrometry in the oh vibrational range 3 000 3 800 cm 1 the 335 crystal grains were extracted from 174 different specimens of yakutian upper mantle material including 97 xenoliths that represent all the rock types occurring in all the kimberlites of the siberian shield the other specimens were mega and macrocrysts or inclusions in diamonds and garnets analysis of the polarised oh spectra allowed distinction between hydroxyl in non intrinsic separate inclusions nsi and in isolated local or condensed extended defects intrinsic to the olivines ild or ced respectively as the two latter types cannot be distinguished by vibrational spectroscopy and as they are presumably interconnected by intracrystalline condensation reactions of the type n ild ced n we propose to symbolise them as ild ced of the total of 70 polarised oh bands that were found in the whole set 17 are caused by nsi 53 by ild ced total mean integrated oh band intensities int total with int a b c int 3 were determined from the spectra they yielded the contents of structurally unallocated water using the recent calibration of the ir method bell et al 2003 the range is 0 a b at 3 327 3 328 cm 1 an energy typical of oh in hydrous wadsleyite we assume this phase to be present as nis in the respective olivines possibly as relic phase 4 weak bands between 3 175 and 3 260 cm 1 polarised along c are tentatively assigned to molecular water nsi with relatively strong hydrogen bonds to the matrix we did not find larger clusters of molecular water i e liquid like water with its characteristic broad band centred at ca 3 400 cm 1 we did also not find any humite minerals as an nsi of the 53 oh bands intrinsic to olivine the 29 most abundant and strong ones were subject to further analysis in terms of oh bearing structural defects ild ced nearly all these bands are strongly polarised along a two bands at 3 672 and 3 535 cm 1 are assigned to boron related defects ild ced b five bands at 3 573 3 563 3 541 3 524 and 3 512 cm 1 are intensity correlated and are assigned to si depleted titan clinohumite like defects ild ced thl the other so far unidentified oh of ild ced are suggested to originate from oh in different types of mg fe depleted defects recently predicted and discovered by tem these are called ild ced kwk eight mostly strong bands of them occur at energies higher than 3 573 cm 1 ild ced kwk h 13 strong to medium strong bands occur below 3 500 cm 1 ild ced kwk l such intrinsic defects may occur alone ild ced thl and ild ced kwk h or in different combinations with each other ild ced kwk h ild ced thl ild ced kwk h ild ced kwk l and ild ced kwk h ild ced thl ild ced kwk l though there are indications that the occurrences of such types and combinations of the intrinsic oh bearing defects in the olivines are related to the types and genetic peculiarities of their host rocks straightforward and simple correlations do not exist the reasons for this and also for the great number of varieties of intrinsic ild ced are discussed

quantification of climate and vegetation from southern african middle stone age sites an application using late pleistocene plant material from sibudu south africa abstract in southern africa numerous middle stone age msa sites document important steps in technological and behavioural development leading to significant changes in the lifeways of modern humans to assess whether these cultural changes and developments may be related to environmental changes we need to ascertain past environments to do this we apply a new quantitative method the gis based coexistence approach cagis on fossil plant material from the msa site sibudu kwazulu natal south africa previous qualitative environmental interpretations of the fossil fauna and flora of the site remain ambiguous because much of the material is anthropogenically introduced it is difficult to distinguish between the effects of natural changes in the local vegetation and behavioural changes of the people that inhabited the shelter cagis can be applied to such biased assemblages and seems to be an adequate method to directly quantify palaeoclimate and vegetation parameters at an archaeological site the cagis analysis shows that during the howiesons poort hp industry winters were slightly colder and drier than present whereas during summer temperatures and precipitation were similar to today post hp winters were drier and colder than present presumably colder than during the hp summer temperatures remained the same but summer precipitation decreased from the hp to post hp vegetation cover was less than today may be even less than during the hp the late msa was observably warmer than the older periods especially during winter at the same time summer precipitation slightly increased and vegetation became more dense but still remained generally open similar to today s anthropogenic landscape generally climatic changes are most pronouncedly reflected in winter temperature parameters especially in minimum winter temperatures and to a lesser extent by changes in summer precipitation the observed ecological trends seem to be affected mainly by variations through time in winter temperatures this refinement of interpretation was not discernible using previous methods for analysing the sibudu data

three water sites in upper mantle olivine and the role of titanium in the water weakening mechanism 1 infrared spectroscopy on synthetic olivines has established that there are at least four different mechanisms by which hydrogen is incorporated into the crystal structure two mechanisms occur in the system mgo sio2 h2o associated with silicon and magnesium vacancies respectively a third mechanism is associated with trivalent cation substitution commonly fe3 in natural olivine while the fourth mechanism which is the one most prevalent in natural olivines from the spinel peridotite facies of the earth s upper mantle is associated with ti4 berry et al 2005 here first principles calculations based on density functional theory are used to derive the structure and relative energies of the two defects in the pure mgo sio2 h2o system and possible hydrogen bearing and hydrogen free point defects in ti4 doped forsterite calculated structures are used to compare the predicted orientation of the o h bonds with the experimentally determined polarization the energies are used to discuss how different regimes of chemical environment temperature t pressure p and both water content and water fugacity f h2o impact on which of the different hydroxyl substitution mechanisms are thermodynamically stable we find that given the presence of ti impurities the most stable mechanism involves the formation of silicon vacancies containing two protons charge balanced by a ti4 cation occupying an adjacent octahedral site this mechanism leads to the water mediated formation of silicon vacancies as silicon is known to be the most slowly diffusing species in olivine this provides a credible explanation of the observed water weakening effect in olivine

south african palaeoenvironments during marine oxygen isotope stage 4 a context for the howiesons poort and still bay industries abstract spanning the period from 74 58 ka and being broadly coeval with marine oxygen isotope stage 4 mis 4 the still bay and howiesons poort industries represent important phases in the development of the material culture of early modern humans how and why these industries occurred when they did however remain matters for speculation a key element of this debate has been the question of what role environmental change during the early stages of the last glacial period may have had on influencing human activity unfortunately well dated palaeoenvironmental evidence from this period is limited and the debate has out of necessity been driven by the application of conceptual models of environmental change many of which associate colder and warmer global climates with increased aridity and humidity respectively in this paper the regional marine and terrestrial evidence is synthesised to create an evidence based palaeoenvironmental context based on the information available to date it appears that rather than being characterised by dry conditions mis 4 was a period of relatively cool moist climates the ubiquity of which transcends the modern regional climate boundaries it is suggested that orbital parameters at this time created greater interaction between tropical and temperate circulation systems bringing more moisture to the subcontinent these findings highlight the distinct nature of southern african climate systems and caution against the application extra regional conceptual models or inferring linear relationships with polar records

chronostratigraphic assignment of volcanopelagic strata above the coast range ophiolite the chronostratigraphic assignments of radiolarian cherts tuffaceous mudstones and volcaniclastic strata referred to herein as volcanopelagic succession overlying the coast range ophiolite in the coast ranges of california have been refined on the basis of additional field data and recent revision of the pessagno and others radiolarian biostratigraphic zonation for the middle and upper jurassic of north america revision of this zonation scheme accomplished through the integration of radiolarian data with ammonite biostratigraphy and geochronometry has enabled close correlation of radiolarian assemblages in north america europe and japan however major differences still exist in the stage assignments of these assemblages among different zonations the pessagno and others scheme is utilized herein to discuss the current chronostratigraphic assignments at five localities in the coast ranges point sal stanley mountain cuesta ridge and llanada in the southern coast ranges and black mountain geyser peak area in the northern coast ranges of california stage assignments for volcanopelagic successions in these areas range from uppermost callovian lower oxfordian to upper tithonian

olivine hydration in the deep upper mantle effects of temperature and silica activity 1 although water controls the biology and geology of the surface hydrogen is perhaps the most poorly constrained compositional variable in the bulk earth its concentration in the upper mantle appears to be controlled by its solubility as hydroxyl in the nominally anhydrous silicate phases olivine pyroxene garnet wadsleyite and ringwoodite here we describe a series of experiments showing that the solubility of h2o in olivine at 12 gpa increases with temperature to 8900 ppm by weight at 1250 c and decreases at higher temperature with the onset of melting sample characterization by infrared spectroscopy indicates that the primary hydration mechanism is the substitution of 2h for mg2 similar results obtained from samples coexisting with clinohumite low silica and with clinoenstatite high silica indicate that silica activity has minimal effect on hydration under these conditions single crystal x ray diffraction measurements constrain the volume of hydration and indicate significant m site vacancies hydrogen thus appears to become a geochemically compatible element as depths approach 400 km

new data on the avifauna from the middle stone age layers of sibudu cave south africa taphonomic and palaeoenvironmental implications abstract the results of a detailed taxonomic and taphonomic study of the bird assemblage from all excavated middle stone age msa layers from sibudu cave wadley s excavations a rock shelter in kwazulu natal south africa are presented here throughout the sequence the assemblage is characterised by the richest taxonomic diversity observed in msa deposits from southern africa while pigeons and doves clearly dominate the bird assemblage the presence of several previously unidentified taxa associated with evergreen and deciduous forest such as woodpeckers turacos hornbills and parrots picidae musophagidae bucerotidae and psittacidae in the pre still bay still bay and howiesons poort layers are useful to document the habitats surrounding sibudu cave from 75 000 to 60 000 years ka ago birds associated with fresh water namely waders charadriidae and scolopacidae and kingfishers alcedinidae are present throughout the layers and are consistent with the proximity of the uthongathi river a study of the general bone preservation implies a shift in the modes of introduction of the birds into the archaeological sediments from a predominantly natural origin accumulation by a bird of prey most likely a falcon in the pre still bay layers to a greater anthropogenic contribution in the still bay and howiesons poort layers

the partitioning of water between olivine orthopyroxene and melt synthesised in the system albite forsterite h2o coexisting forsterite enstatite and silicate glass were synthesised from a water bearing basalt analogue in programmed cooling experiments at 1 0 1 5 2 0 and 2 5 gpa hydrous species in each phase were characterised and quantified using infrared absorbance spectroscopy al 3 related hydroxyl defects with vibrational energies between 3400 3200 cm 1 dominate the hydroxyl budget of synthetic forsterite the vibrational characteristics of these defects indicate that similar absorptions in febearing systems result from fe 3 related oh species this interpretation resolves a previously recognised but unexplained relationship between oxygen fugacity and hydroxyl speciation in experimentally annealed olivines and suggests that the intensities of bands at 3400 3300 cm 1 could form the basis of an oxybarometer oh defect speciation in enstatite is similar to that in aluminous crystals synthesised at high water fugacity and many natural orthopyroxenes hydroxyl speciation in orthopyroxene is not therefore controlled by water activity total water contents of synthetic enstatites from any single experiment vary enormously this heterogeneity is attributed to variable contributions from a non intrinsic broad band hydrous component intrinsic hydroxyl concentrations dissolved in enstatite are identical in all crystals from an experiment the partitioning of water between forsterite enstatite and coexisting silicate melt is independent of pressure temperature and total water content over the range of conditions studied as long as the influence of these parameters on phase compositions is taken into account dh2o fo melt 0 0001 0 0003 n 4 and is insensitive to pressure or olivine aluminium contents dh2o en melt is strongly controlled by al2o3 concentration and ranges from 0 003 0 016 n 6 two samples contain both forsterite and enstatite and yield dh2o en fo 25 1

the effect of silica activity on the incorporation mechanisms of water in synthetic forsterite a polarised infrared spectroscopic study pure forsterite crystals were grown from hydrous melts using controlled cooling experiments at 2 0 gpa and varying the bulk mg si ratio from 2 0 to 1 5 oriented single crystals were then studied by polarised infrared spectroscopy the spectra of the samples with the lowest silica activity asio2 contain the main oh bands in the range 3 620 3 450 cm 1 only in contrast the spectra of the samples synthesised with the highest asio2 contain additional pleochroic bands at 3 160 3 220 and 3 600 cm 1 the variations are interpreted in terms of protonated silicon vacancies being dominant at low asio2 and mg vacancies dominant at high asio2 xenolithic mantle olivines generally do not have the spectrum expected for orthopyroxene buffered conditions suggesting that they re equilibrated with their host melts during ascent but mantle olivine from the zabargad peridotite massif probably is in equilibrium with the coexisting orthopyroxene

effect of oxygen fugacity on the h2o storage capacity of forsterite in the carbon saturated systems abstract high pressure experiments have been performed in the systems mg 2 sio 4 c o h and mg 2 sio 4 k 2 co 3 c at 6 3 gpa and 1200 to 1600 c using a split sphere multi anvil apparatus in the mg 2 sio 4 c o h system the composition of fluid was modeled by adding different amounts of water and stearic acid the f o 2 was controlled by the mo moo 2 or fe feo oxygen buffers several experiments in the mg 2 sio 4 c o h system and all experiments in the mg 2 sio 4 k 2 co 3 c system have been conducted without buffering the f o 2 forsterite in the system mg 2 sio 4 k 2 co 3 c does not reveal oh absorption bands in the ir spectra while forsterite coexisting with carbon bearing fluid and silicate melt at log f o 2 from fmq 2 to fmq 5 from 2 to 5 log units below fayalite magnetite quartz oxygen buffer contains 800 1850 wt ppm h 2 o the maximum concentrations were detected at 1400 c and fmq 3 5 we observed an increase in the solidus temperature in the system mg 2 sio 4 c o h from 1200 to above 1600 c with log f o 2 decreasing from fmq 2 to fmq 5 the increase of the solidus temperature and the broadening of the stability field of the h 2 o h 2 ch 4 subsolidus fluid phase at 1400 1600 c explain the high h 2 o storage capacity of forsterite relative to that crystallized from carbon free oxidized hydrous silicic melt at temperatures above 1400 c liquidus forsterite precipitated along with diamond from oxidized fmq 1 carbonate silicate melt and from silicate melt dissolving the moderately reduced c o h fluid from fmq 2 to fmq 3 5 formation of diamond was not detected under ultra reduced conditions fmq 5 at 1200 1600 c olivine co precipitating with diamond from dry carbonate silicate or hydrous silicic fluid melt can provide information on the h 2 o contents and speciation of the diamond forming media in the mantle the conditions for minimum post crystallization alteration of olivine and its hydrogen content are discussed

in situ infrared spectra of oh in olivine to 1100 c the infrared spectra of hydrated san carlos olivine were measured from room temperature to 1100 c at 1 bar using a heating stage the spectra show that even at the highest temperatures studied there are still two well separated groups of oh bands centered between 3200 and 3300 cm 1 and between 3500 and 3600 cm 1 respectively the distinction between group i 3450 cm 1 and group ii bands 3450 cm 1 is therefore still meaningful at upper mantle temperatures however a prominent band at 3612 cm 1 already loses intensity by 100 c and nearly disappears by 300 c suggesting that it corresponds to a particular h environment that only formed during cooling of the sample and that it is not stable at high temperature a similar band is prominent in many olivines from mantle xenoliths and previously it has sometimes been assigned to oh groups surrounding si vacancies we show that structural models of water dissolution in olivine derived from infrared spectra at ambient conditions may not be fully applicable for the upper mantle

ftir spectrum of phenocryst olivine as an indicator of silica saturation in magmas fourier transform infrared ftir absorption spectra of hydroxyl were measured on olivine phenocrysts from hydrous basaltic melts that originated in island arc tectonic settings the basaltic melts encompass a wide range of silica activities from orthopyroxene saturated hypersthene normative to nepheline normative compositions the intensities and wavenumber placement of hydroxyl absorption bands correlate with the degree of silica saturation of the parent melt from which the olivine crystallized olivines from silica undersaturated nepheline normative melts absorb ir radiation in the wavenumber range 3430 3590 cm 1 group 1 in contrast olivines from orthopyroxene saturated boninitic melts exhibit hydroxyl absorption bands in the wavenumber range 3285 3380 cm 1 group 2 olivines crystallized at intermediate silica activities exhibit a combination of the two groups of hydroxyl ir bands where the proportion of group 2 bands increases with increasing silica saturation of the parent melt the positions of hydroxyl absorption peaks observed here for natural samples are consistent with previous measurements on experimentally annealed olivines thus protonation experiments can be employed to make spectroscopically dry olivine structures visible by ir yielding information on the silica saturation of the parental magmas hydroxyl concentrations in the studied olivines were estimated to be 1 2 ppm corresponding to an olivine melt partition coefficient of similar to 1 0 0 3 x 10 4

isotopic and trace element composition of volcanic glasses from the akaki canyon cyprus implications for the origin of the troodos ophiolite abstract we report major elements k rb cs sr ba sc cr ni hf ta th and ree concentrations and isotopic compositions of sr nd pb and o of carefully handpicked volcanic glasses from the akaki river section of the troodos ophiolite complex on the basis of sr and o isotopic composition and fe 2 o 3 feo ratios nine of the ten glasses analyzed are considered to be fresh even with respect to those elements that are easily affected by alteration the glasses range in composition from basaltic andesite to dacite incompatible element concentrations in the mafic compositions are low 10 chondritic and the light ree are strongly depleted however the ratios of low field strength elements k rb cs sr th to high field strength elements ta hf ti and rare earth elements are higher than those in n morb nd isotopic compositions show a very small range with e nd t 80ma varying from 6 5 to 7 5 initial 87 sr 86 sr ratios range from 0 7033 to 0 7040 pb isotope ratios have a restricted range with 206 pb 204 pb 18 60 18 70 207 pb 204 pb 15 55 15 59 and 208 pb 204 pb 38 08 38 51 the oxygen isotopic composition for fresh glasses falls within the range reported for fresh mafic mantle derived volcanics with 18 o varying from 5 4 to 6 5 all geochemical characteristics of the troodos volcanic glasses are similar to those observed in supra subduction zone volcanics but we cannot distinguish between an early stage island arc or back arc origin for the troodos ophiolite on a geochemical basis only however considering our data and previously published geologic and geochemical data we suggest that the troodos ophiolite formed in the earliest stages of island arc development

water in natural olivine determined by proton proton scattering analysis here we present water concentration data for olivine from different host rocks measured with a nuclear technique using proton proton scattering this method which is used here for the first time on olivine is very powerful for determining trace amounts of water the studied olivine specimens differ in their h 2 o contents ranging from 4 to 51 wt ppm 10 117 atom ppm h the lowest concentrations are found in olivine from spinel peridotite xenoliths the highest concentrations in olivine from alpine type peridotite the contents of an ophiolitic and a hydrothermal olivine are intermediate infrared spectroscopy was applied to ensure that the measured water contents stem solely from hydroxyl defects in the mineral structure the infrared spectra differ from sample to sample five of six olivine specimens show absorption bands typical of hydroxyl groups associated with ti defects these olivines differ in their ti contents by two orders of magnitude however a correlation of water and ti content was not observed

test of the eepas forecasting model on the japan earthquake catalogue the eepas every earthquake a precursor according to scale model is a method of forecasting earthquakes based on the notion that the precursory scale increase phenomenon occurs at all scales in the seismogenic process the rate density of future earthquake occurrence is computed directly from past earthquakes in the catalogue the eepas model has previously been fitted to the new zealand earthquake catalogue and successfully tested on the california catalogue

geochemical evidence for the tectonic setting of the coast range ophiolite a composite island arc oceanic crust terrane in western california the middle to late jurassic age coast range ophiolite cro of california contains two geochemically distinct volcanic rock associations that formed in different tectonic settings volcanic rocks from the southern cro point sal cuesta ridge stanley mountain llanada quinto creek and del puerto and parts of the northern cro healdsburg elder creek are similar to low k tholeiites and calc alkaline rocks of the island arc suite the thin volcanic sections of these ophiolite remnants suggest formation by intra arc rifting in contrast volcanic rocks from stonyford seamount and paskenta in the northern cro are transitional subalkaline metabasalts with geochemical characteristics similar to enriched mid ocean ridge basalts or ocean island tholeiites these rocks are associated with tithonian radiolarian cherts and may be part of the franciscan complex alternatively they may represent a change in tectonic setting within the cro during the late jurassic regardless the cro as currently conceived cannot be considered a single terrane with one mode of origin

the infrared signature of water associated with trivalent cations in olivine abstract forsterite crystals were synthesised under water saturated conditions at 1400 c and 1 5 gpa doped with trace amounts of either b al sc ti v cr mn fe co ga y zr in sm gd dy tm or lu the common and intense hydroxyl stretching bands in the infrared spectra of spinel peridotite olivine at 3572 and 3525 cm 1 were only reproduced in the presence of ti those samples where the trace element substitutes as the trivalent cation on the mg 2 site were identified from a systematic variation in concentration with the trivalent ionic radius the hydroxyl region of all samples is essentially identical except for between 3300 and 3400 cm 1 this region is characterised by one or more bands with the energy of the most intense feature being correlated with the ionic radius of the trivalent cation the integrated intensity of these hydroxyl bands also correlates with the concentration of the trivalent cation these correlations provide unambiguous evidence that bands or peaks in this region correspond to water at defect sites associated with trivalent cations trivalent peaks are sometimes observed in samples of mantle olivine and most likely indicate water associated with fe 3 the water at this site is not incorporated under normal mantle conditions and should not be included in estimates of the water capacity of mantle olivine these results emphasise the importance of identifying the infrared signature of different water substitution mechanisms

the effect of oxygen fugacity on hydroxyl concentrations and speciation in olivine implications for water solubility in the upper mantle the effect of oxygen fugacity on hydroxyl speciation and solubility in san carlos olivine was investigated in a series of piston cylinder experiments at 2 0 gpa and 1100 and 1300 c the presence of enstatite was intended to fix silica activity and experimental fo2 in most runs was regulated by lining the inner walls of the sample containing pt capsules with either fe ni or re foil polarised infrared absorbance spectra show that olivine annealed in capsules lined with fe foil only contain hydroxyl defects with vibrational energies between 3650 and 3400 cm 1 relatively high frequencies spectra of crystals annealed in capsules lined with ni or re foil show that these samples contain hydroxyl defects with vibrational energies between 3650 and 3400 cm 1 high frequency and at 3355 and 3325 cm 1 low frequency the concentrations of hydroxyl defects responsible for absorptions at 3355 and 3325 cm 1 change as a function of oxygen fugacity and are therefore interpreted as fe 3 related oh centres hydroxyl solubility in our experiments is substantially less than current solubility laws might suggest these differences may be attributed to variations in experimental procedure but they also demonstrate that the incorporation of hydroxyl in olivine must be betterunderstoodbeforeanaccuratemodeltodescribewatersolubilityinthedeepearthcanbeconstructed ourdatashowthat when experiments conductedat identicalp tconditionsarecompared olivine annealedat lowf o2 below fe feo contains lessthanhalf as much water as crystals from relatively more oxidised experiments because natural mantle conditions approximate to those of our low fo2 experiments current solubility laws which are based on data from relatively high f o2 experiments overestimate the amount of water that can be hosted in olivine in the upper mantle from a consideration of defect equilibria we propose a mechanism for the incorporation of oh in olivine in a way that is appropriate for the actual range of conditions expected in the mantle 2007 elsevier b v all rights reserved

earthquake recurrence in simulated fault systems we employ a computationally efficient fault system earthquake simulator rsqsim to explore effects of earthquake nucleation and fault system geometry on earthquake occurrence the simulations incorporate rate and state dependent friction high resolution representations of fault systems and quasi dynamic rupture propagation faults are represented as continuous planar surfaces surfaces with a random fractal roughness and discontinuous fractally segmented faults simulated earthquake catalogs have up to 106 earthquakes that span a magnitude range from m4 5 to m8 the seismicity has strong temporal and spatial clustering in the form of foreshocks and aftershocks and occasional large earthquake pairs fault system geometry plays the primary role in establishing the characteristics of stress evolution that control earthquake recurrence statistics empirical density distributions of earthquake recurrence times at a specific point on a fault depend strongly on magnitude and take a variety of complex forms that change with position within the fault system because fault system geometry is an observable that greatly impacts recurrence statistics we propose using fault system earthquake simulators to define the empirical probability density distributions for use in regional assessments of earthquake probabilities

thermodynamics of water solubility and partitioning when it was realized that nominally anhydrous minerals could be a major storage site of water in the mantle smyth 1987 bell and rossman 1992 it also became rather obvious that many mantle samples probably have lost most of their water during ascent e g ingrin and skogby 2000 while analyses of natural samples therefore in many circumstances only provide a lower limit of the actual water content in the mantle measurements of water solubility give an upper limit of the amount of water that might be stored in a mineral experimental measurements of water solubility have therefore naturally evolved in the last decades as a major tool for understanding the water storage capacity of the mantle closely related to studies of water solubility are studies of water partitioning among minerals if the water solubility in two minerals is known under given conditions the partition coefficient is just the ratio of the water solubilities under the same conditions provided that the composition of the fluid coexisting with the two minerals is the same since the pioneering work of bai and kohlstedt 1992 and of kohlstedt et al 1996 the water solubility in all major upper mantle minerals has been studied as well as the partitioning of water between the minerals of the lower mantle and the transition zone solubility studies by themselves do not directly give the water content in the mantle they constrain the storage capacity of the mantle i e the maximum amount of water that may be stored if the mantle were water saturated however as most of the mantle is very likely water undersaturated the actual water content is probably far below the storage capacity estimates of the actual abundance and distribution of water in the mantle may be obtained by combining solubility and partitioning data with direct

balancing the plate motion budget in the south island new zealand using gps geological and seismological data summary the landmass of new zealand exists as a consequence of transpressional collision between the australian and pacific plates providing an excellent opportunity to quantify the kinematics of deformation at this type of tectonic boundary we interpret gps geological and seismological data describing the active deformation in the south island new zealand by using an elastic rotating block approach that automatically balances the pacific australia relative plate motion budget the data in new zealand are fit to within uncertainty when inverted simultaneously for angular velocities of rotating tectonic blocks and the degree of coupling on faults bounding the blocks we find that most of the plate motion budget has been accounted for in previous geological studies although we suggest that the porter s pass amberley fault zone in north canterbury and a zone of faults in the foothills of the southern alps may have slip rates about twice that of the geological estimates up to 5 mm yr 1 of active deformation on faults distributed within the southern alps 100 km to the east of the alpine fault is possible the role of tectonic block rotations in partitioning plate boundary deformation is less pronounced in the south island compared to the north island vertical axis rotation rates of tectonic blocks in the south island are similar to that of the pacific plate suggesting that edge forces dominate the block kinematics there the southward migrating chatham rise exerts a major influence on the evolution of the new zealand plate boundary we discuss a model for the development of the marlborough fault system and hikurangi subduction zone in the context of this migration

national seismic hazard model for new zealand 2010 update a team of earthquake geologists seismologists and engineering seis mologists has collectively produced an update of the national probabilistic seismic hazard psh model for new zealand national seismic hazard model or nshm the new nshm supersedes the earlier nshm published in 2002 and used as the hazard basis for the new zealand loadings standard and numerous other end user applica tions the new nshm incorporates a fault source model that has been updated with over 200 new onshore and offshore fault sources and utilizes new new zealand based and international scaling relationships for the parameterization of the faults the dis tributed seismicity model has also been updated to include post 1997 seismicity data a new seismicity regionalization and improved methodology for calculation of the seismicity parameters probabilistic seismic hazard maps produced from the new nshm show a similar pattern of hazard to the earlier model at the national scale but there are some significant reductions and increases in hazard at the regional scale the national scale differences between the new and earlier nshm appear less than those seen between much earlier national models indicating that some degree of consis tency has been achieved in the national scale pattern of hazard estimates at least for return periods of 475 years and greater online material table of fault source parameters for the 2010 national seismic hazard model

the bearded vulture gypaetus barbatus as an accumulator of archaeological bones late glacial assemblages and present day reference data in corsica western mediterranean assemblages of 751 bone remains of an endemic corsican deer megaloceros cazioti from late glacial layers at luri gritulu cave northern corsica show an uncommon taphonomic pattern mainly characterized by high dominance of third phalanxes and high rate of digestion marks the authors demonstrate that this pattern cannot result from accumulation by human beings or by large mammal carnivores the bearded vulture which is able to accumulate large mammal bones in its nest and the presence of which is attested in the faunal remains at gritulu is the principal putative accumulator in order to test this hypothesis bone contents from 11 nests of modern corsican bearded vultures 871 bone remains i e more than 105 individual carcasses are analysed from a taphonomic point of view they are mainly characterized by overwhelming quantities of third phalanxes from middle size ruminants abundance and location of digestion marks around proximal articulations and few bone flakes a comparison of the gritulu cave assemblages with these new present day reference data leads to the conclusion that they have actually been accumulated by late glacial bearded vultures small discrepancies can however be explained by differences in food availability between the late glacial and modern times