the response of the southwest western australian wave climate to indian ocean climate variability knowledge of regional wave climates is critical for coastal planning management and protection in order to develop a regional wave climate it is important to understand the atmospheric systems responsible for wave generation this study examines the variability of the southwest western australian swwa shelf and nearshore wind wave climate and its relationship to southern hemisphere climate variability represented by various atmospheric indices the southern oscillation index soi the southern annular mode sam the indian ocean dipole mode index dmi the indian ocean subtropical dipole iosd the latitudinal position of the subtropical high pressure ridge strp and the corresponding intensity of the subtropical ridge stri a 21 year wave hindcast 1994 2014 of the swwa continental shelf was created using the third generation wave model simulating waves nearshore swan to analyse the seasonal and inter annual wave climate variability and its relationship to the atmospheric regime strong relationships between wave heights and the strp and the stri a moderate correlation between the wave climate and the sam and no significant correlation between soi dmi and iosd and the wave climate were found strong spatial seasonal and inter annual variability as well as seasonal longer term trends in the mean wave climate were studied and linked to the latitudinal changes in the subtropical high pressure ridge and the southern ocean storm belt as the southern ocean storm belt and the subtropical high pressure ridge shifted southward northward wave heights on the swwa shelf region decreased increased the wave height anomalies appear to be driven by the same atmospheric conditions that influence rainfall variability in swwa

the solubility of nb ta zr hf w in granitic melts with li and li f constraints for mineralization in rare metal granites and pegmatites tantalum mineralization is associated with granites and pegmatites that invariably are rich in lithium this in part is due to the extreme fractionation that is necessary for melts to reach saturation in either a ta or an li phase however there may also be chemical interactions in melts that explain this association experiments therefore were conducted to determine the effect of lithium on the solubility of tantalite mnta 2 o 6 in water saturated granitic melts other important elements in rare metal granites include nb zr hf and w consequently the effect of li on the solubilities of columbite mnnb 2 o 6 zircon zrsio 4 hafnon hfsio 4 and hbnerite mnwo 4 in granitic melts was also investigated the haplogranitic melt compositions used in these experiments have constant mole percent si and al and the al li na k ratio was 1 0 for all experiments i e the lithium content was the only compositional variable columbite and tantalite solubilities in the granitic liquids increase by a factor of approximately 2 to 3 with the addition of 2 wt percent li 2 o to haplogranite at 750 degrees to 1 035 degrees c 2 kbars and water saturated conditions the solubility data were extrapolated to a lower temperature more reasonable for columbite tantalite crystallization then compared to compositions representative of evolved liquids from which rare metal granites and pegmatites crystallize it is estimated that at 600 degrees c these melt compositions could be saturated in columbite but not tantalite however tantalite saturation is predicted if the melts contained less li and f therefore the genesis of tantalum mineralization may be explained by ta being retained in the melt because of high li f concentrations tantalite crystallization is delayed until an li or f or p mineral crystallizes which lowers tantalite solubility and results in a general association of ta with li in mineralized granitic rocks in contrast to columbite and tantalite the solubility of wolframite is not affected by the lithium content of the melt with up to 3 8 wt li 2 o in starting glasses and the solubilities of zircon and hafnon decrease with increasing li content of the melt one possible interpretation of the hbnerite solubility data is that the melt contains dominantly w super 6 which behaves as a network former the decrease in zircon hafnon solubility with li may reflect the lower field strength of zr super 4 and hf super 4 compared to nb super 5 and ta super 5 i e zr and hf are less able to compete with li for nonbridging oxygens whereas nb and ta are more able to compete it is also significant that the solubility of hafnon is greater than that of zircon similar to the higher solubility of tantalite compared to columbite this can explain why zr hf and nb ta ratios both decrease with fractionation

weak faults rotten cores earthquakes are triggered when crustal deformation produces displacements along fault zones the rock in these zones is found to be weaker than adjacent material but what are the mechanisms of this loss of strength in his perspective holdsworth 1 discusses how recent studies of exposed ancient fault zones combined with laboratory analyses are revealing that rock properties at the grain scale can determine the large scale behavior of crustal deformation 1 http www sciencemag org cgi content full 303 5655 181

magmatic hydrothermal processes recorded by muscovite andcolumbite group minerals from the bailongshan rare element pegmatites in the west kunlun karakorum orogenic belt nw china abstract the mineralization of rare element pegmatites is attributed to complex magmatic hydrothermal processes such as magma fractionation fluid exsolution and fluid melt metasomatism however it is still unclear how these processes affect the evolution of pegmatites and the fractionation of rare elements here we use the textures and major and trace element compositions of muscovite and columbite group minerals cgm from the newly discovered bailongshan li cs ta lct type pegmatites in the west kunlun karakorum orogenic belt nw china to decipher the magmatic hydrothermal processes related to enrichment of rare elements four major regional zones are recognized in the bailongshan area quartz albite tourmaline qat zone quartz muscovite qm zone quartz albite spodumene qas zone and quartz spodumene qs zone the qat and qm zones are barren whereas the qas and qs zones host six major li rb ore segments i to vi along the nww see strike from the qm zone through the qas to the qs zone the k rb ratios of muscovite decrease gradually from 26 0 to 7 8 and cgm has mn s increasing from 0 28 to 0 56 consistent with the trend of progressive evolution of the pegmatites the ta profiles across individual cgm grains reveal a three stage growth process i e from a nb rich cgm magmatic stage to a ta rich cgm magmatic stage to a nb rich cgm hydrothermal stage high resolution elemental mapping of primary muscovite from the qas and qs zones shows that melt metasomatism induced local enrichment of f li cs and ta and the precipitation of secondary lepidolite along the rims or cleavages of primary muscovite in addition late stage f poor fluid metasomatism caused the release of fe mn b rb and cs from primary muscovite and induced complex zoning patterns and crystallization of hydroxylapatite in cleavage planes of primary muscovite secondary muscovite has higher li be b rb and cs and lower nb than primary muscovite indicating that these elements may have been partially dissolved and remobilized from primary spodumene muscovite and cgm into late stage hydrothermal fluids from which the secondary muscovite and nb rich cgm crystallized therefore the complex zoning patterns and compositional variations of both muscovite and cgm from the bailongshan pegmatites record a progressive magmatic hydrothermal process related to the rare metal mineralization

melt inclusions in pegmatite quartz complete miscibility between silicate melts and hydrous fluids at low pressure fluorine boron and phosphorus rich pegmatites of the variscan ehrenfriedersdorf complex crystallized over a temperature range from about 700 to 500 c at a pressure of about 1 kbar pegmatite quartz crystals continuously trapped two different types of melt inclusions during cooling and growth a silicate rich h2o poor melt and a silicate poor h2o rich melt both melts were simultaneously trapped on the solvus boundaries of the silicate fluorine boron phosphorus water system the partially crystallized melt inclusions were rehomogenized at 1 kbar between 500 and 712 c in steps of 50 c by conventional rapid quench hydrothermal experiments glasses of completely rehomogenized inclusions were analyzed for h2o by raman spectroscopy and for major and some trace elements by emp electron microprobe both types of melt inclusions define a solvus boundary in an xh2o t pseudobinary system at 500 c the silicate rich melt contains about 2 5 wt h2o and the conjugate water rich melt about 47 wt h2o the solvus closes rapidly with increasing temperature at 650 c the water contents are about 10 and 32 wt respectively complete miscibility is attained at the critical point 712 c and 21 5 wt h2o many pegmatites show high concentrations of f b and p this is particularly true for those pegmatites associated with highly evolved peraluminous granites the presence of these elements dramatically reduces the critical pressure for fluid melt systems at shallow intrusion levels at t 720 c water is infinitely soluble in a f b and p rich melt simple cooling induces a separation into two coexisting melts accompanied with strong element fractionation on the water rich side of the solvus very volatile rich melts are produced that have vastly different physical properties as compared to normal silicate melts the density viscosity diffusivity and mobility of such hyper aqueous melts under these conditions are more comparable to an aqueous fluid

the behavior of trace elements during the chemical evolution of the h 2 o b and f rich granite pegmatite hydrothermal system at ehrenfriedersdorf germany a sxrf study of melt and fluid inclusions detailed melt and fluid inclusion studies in quartz hosts from the variscan ehrenfriedersdorf complex revealed that ongoing fractional crystallization of the highly evolved h2o b and f rich granite magma produced a pegmatite melt which started to separate into two immiscible phases at about 720 c 100 mpa with cooling and further chemical evolution the immiscibilty field expanded two conjugate melts a peraluminous one and a peralkaline one coexisted down to temperatures of about 490 c additionally high salinity brine exsolved throughout the pegmatitic stage along with low density vapor towards lower temperatures a hydrothermal system gradually developed boiling processes occurred between 450 and 400 c increasing the salinities of hydrothermal fluids at this stage below the late hydrothermal stage is dominated by low salinity fluids using a combination of synchrotron radiation induced x ray fluorescence analysis and raman spectroscopy the concentration of trace elements mn fe zn as sb rb cs sr zr nb ta ag sn ta w rare earth elements ree and cu was determined in 52 melt and 8 fluid inclusions that are representative of distinct stages from 720 c down to 380 c homogenization temperatures and water contents of both melt and fluid inclusions are used to estimate trapping temperatures thus revealing the evolutionary stage during the process trace elements are partitioned in different proportions between the two pegmatite melts high salinity brines and exsolving vapors concentrations are strongly shifted by co ncomitant crystallization and precipitation of ore forming minerals for example pegmatite melts at the initial stage 700 c have about 1 600 ppm of sn concentrations in both melts decrease towards lower temperatures due to the crystallization of cassiterite between 650 and 550 c tin is preferentially fractionated into the peralkaline melt by a factor of 2 3 while the last pegmatite melts are low in sn 64 ppm at 500 c early hydrothermal fluids become again enriched with about 800 ppm of sn at the boiling stage a sudden drop in late hydrothermal fluids 23 ppm of sn at 370 c results from precipitation of another cassiterite generation between 400 and 370 c zinc concentrations in peraluminous melts are low some tens of parts per million and are not correlated with temperature in coexisting peralkaline melts and high t brines they are higher by a factor of 2 3 zinc continuously increases in hydrothermal fluids 3 000 ppm at 400 c where the precipitation of sphalerite starts the main removal of zn from the fluid system occurs at lower temperatures similarly melt and fluid inclusion concentrations of many other trace elements directly reflect the crystallization and precipitation history of minerals at distinctive temperatures or temperature windows

representation of faults in reservoir scale geomechanical finite element models a comparison of different modelling approaches abstract different approaches exist to incorporate faults in reservoir scale geomechanical models challenges are the proper representation of the fault geometry as well as the small scale variations in the internal architecture and the mechanical properties of the fault zone regarding the typical size of such models i e kilometres to tens of kilometres the present study utilizes a simple generic fault zone model to compare three different possibilities commonly used to represent faults in finite element reservoir models two differ in the basic grid geometry and the arrangement of mechanically weak fault zone elements respectively the third uses a discontinuous grid and contact elements to represent the fault modelling results show remarkable differences in the calculated stress and strain patterns the relatively strongest perturbations result for a continuous curvilinear grid adapted to the fault geometry in contrast the fault implementation has the least impact on local stresses and strains if it is represented as a stair step structure contained in a rectangular grid the use of contact elements has an intermediate effect modelling results are used to infer some general recommendations concerning the appropriate approach of representing faults in a numerical geomechanical reservoir models depending on fault geometry model scale and scope of interest

age of the dahongliutan rare metal pegmatite deposit west kunlun xinjiang nw china constraints from la icp ms u pb dating of columbite fe and cassiterite abstract dahongliutan is a medium size li be ta nb rare metal pegmatite deposit in the tianshuihai terrane west kunlun orogenic belt nw china in this paper la icp ms u pb ages of columbite fe and cassiterite are reported to constrain the metallogenic age columbite fe with high u and low th yielded a late triassic weighted mean 206 pb 238 u age of 211 9 2 4 ma whilst cassiterite yielded a 206 pb 238 u 207 pb 235 u concordia lower intercept age of 218 12 ma and a tera wasserburg lower intercept age of 218 12 ma which is identical to the columbite fe u pb age and thus represents the emplacement age of the pegmatite dikes the ore hosting pegmatite dikes are intimately time space related to the dahongliutan s type granite ca 220 217 ma indicating that they may have been cogenetic integrating new and published geological data we suggest that the dahongliutan pegmatites may have evolved from the granitic magma represented by the dahongliutan s type pluton in a post collisional tectonic setting regionally the tianshuihai terrane is the western extension of the songpan ganzi block and thus the kunlun li mineralization belt may have been connected to the songpan ganzi li mineralization belt which contains eleven lithium deposits with about 9 8 of li 2 o reserves in china implying that the dahongliutan pegmatite deposit may also have favorable ore forming conditions the similar columbite fe and cassiterite ages demonstrate that these minerals can be precisely dated and could provide useful alternatives to accurately constrain the timing and evolution of rare metal mineralization

an experimental study of element partitioning among biotite muscovite and coexisting peraluminous silicic melt at 200 mpa h2o

liquid immiscibility and its role at the magmatic hydrothermal transition a summary of experimental studies several types of fluid immiscibility may affect the evolution of volatile rich magmatic systems at the magmatic hydrothermal transition the topology of silicate salt h2o systems implies that three fluid immiscibility silicate melt hydrosaline melt vapour should be stable in a broad range of compositions and p t conditions the most important factor controlling the immiscibility appears to be the coulombic properties electric charges z and ionic radii r of the main network modifying cations and the capacity for immiscibility appears to decrease in the following sequence mg ca sr ba li na k liquid immiscibility is enhanced in peralkaline compositions and in the presence of nonsilicate anions such as f cl co32 and bo33 in volatile rich magmatic systems the h2o is likely to react with the chloride fluoride borate and carbonate species and the chemical effects of high temperature hydrolysis may be greatly enhanced by phase separation in systems with multiple immiscible fluid phases natural granitic magmas can thus exsolve a range of chemically and physically diverse hydrosaline liquids and the role of these fluid phases is likely to be especially significant in pegmatites and li f rare metal granites

a petrologic assessment of internal zonation in granitic pegmatites abstract cameron et al 1949 devised the nomenclature and delineated the patterns of internal zonation within granitic pegmatites that are in use today zonation in pegmatites is manifested both in mineralogy and in fabric mineral habits and rock texture although internal zonation is a conspicuous and distinctive attribute of pegmatites there has been no thorough effort to explain that mineralogical and textural evolution in relation to the zoning sequence presented by cameron et al 1949 or in terms of the comprehensive petrogenesis of pegmatite bodies pressure temperature and whole rock composition this overview of internal zonation within granitic pegmatites consists of four principal parts 1 a historic review of the subject 2 a summary of the current understanding of the pegmatite forming environment 3 the processes that determine mineralogical and textural zonation in pegmatites and 4 the applications of those processes to each of the major zones of pegmatites based on the concepts presented in london 2008 the fundamental determinates of the internal evolution of pegmatite zones are 1 the bulk composition of melt 2 the magnitude of liquidus undercooling prior to the onset of crystallization 3 subsolidus isothermal fractional crystallization by which eutectic or minimum melts fractionate by sequential non eutectic crystallization 4 constitutional zone refining via the creation of a boundary layer liquid chemically distinct from but continuous with the bulk melt at the crystallization front and 5 far field chemical diffusion the long range and coordinated diffusion of ions particularly of alkalis and alkaline earths through melt

an experimental study of b p and f rich synthetic granite pegmatite at 0 1 and 0 2 gpa extreme enrichment in h2o b p and f is characteristic of many evolved granites and pegmatites we report experimental phase relations of a synthetic peraluminous pegmatite spiked with p2o5 b 2o3 and f 5 wt of each rb2o cs2o 1 wt of each and li2o 0 5 wt experiments were carried out in h2o satu rated conditions in cold seal rapid quench pressure vessels at 0 1 0 2 gpa crystallisation starts at about 820 c with berlinite and topaz quartz appears at 700 750 c topaz is replaced by muscovite at about 600 c at near solidus temperatures 450 500 c amblygonite lacroixite and a cs bearing aluminosilicate crystallise in all charges aluminosilicate melt coexists with low density hydrous fluid and hydrosaline melt the latter is strongly enriched in na3alf6 and h3bo3 components experi mental evidence of the liquid immiscibility and mineral reactions documented in our study offers new explana tions of many enigmatic features of natural pegmatites

experimental partitioning of rb cs sr and ba between alkali feldspar and peraluminous melt hydrous partial melting experiments performed between 650 and 750 c at 200 mpa h20 on synthetic metapelite compositions quartz albite muscovite biotite mineral mixtures doped with ba sr rb and cs yielded alkali feldspar crystals with a wide range of compositions in equilibrium at their rims with peraluminous melt measured partition coefficients for normally trace lithophile elements between feldspar and melt d m fsp gl m ba sr rb cs do not depend on either temperature or bulk composition of melt for the compositions studied values of d sr fsp gl are between 10 and 14 and appear to be independent of the albite and orthoclase contents of the feldspar crystals in contrast values of d ba fsp gl and d rb fsp glare strongly dependent on the orthoclase content of feldspar relationships that can be expressed by the following linear equations d ba fsp gl 0 07 0 25 orthoclase and d rb fsp gl 0 03 0 0 1 orthoclase where orthoclase is in mole percent these equations reproduce the range of previously reported values for d ba and d rb determined on natural and synthetic samples a single partition coefficient for cs was also determined at d cs fsp gl 0 13 these data can be used in conjunction with recently published partition coefficients for muscovite biotite and plagioclase feldspars blundy and wood 1991 icenhower and london 1995 to model quantitatively the trace element signatures of peraluminous magmas during anatexis and crystallization depending on bulk composition and pressuretemperature trajectories during episodes of partial melting ba and sr and to a lesser extent rb are retained at the source while cs and li are enriched in the first melts these results explain why peraluminous granitic magmas with s type sedimentary sources carry a distinctive enrichment in li and cs

revisiting complete miscibility between silicate melts and hydrous fluids and the extreme enrichment of some elements in the supercritical state consequences for the formation of pegmatites and ore deposits abstract using water and major and trace element data obtained from melt inclusions primarily in pegmatite quartz we have shown in this and previous papers that melt melt fluid immiscibility is widespread and an important process during the generation of granitic pegmatites furthermore we have shown that the formation of pegmatites actually begins in the supercritical melt fluid stage in this study we extend previous work and in particular explore the behavior of 10 different elements be f p s cl as rb sn cs and ta in the supercritical range from preliminary studies we suggest that other elements such as b na k zn nb and sb will behave similarly near the solvus crest of a generalized pseudo binary melt water system this provides important evidence that pegmatite forming processes have already begun at high temperatures in the range of 850 750 c and that may require a re think on the partitioning behavior of metals in late stage residual melts exsolved from granitic magmas the existence of this parental supercritical silicate melt fluid although derived from granitic magmas imposes significant constraints of its own so drawing conclusions about pegmatite forming processes from data gained from slightly modified granite compositions becomes highly problematic we propose that the extremely high concentration of some elements over a small but well defined water concentration range symmetrically distributed around the critical point of the pseudo binary solvus must be derived from the unusual properties of the near critical or supercritical phases these unusual properties include extremely low density viscosity and surface tension and high diffusivity reactivity and mobility these are exactly the qualities that make such supercritical fluids an excellent medium for the formations of pegmatites by reactions with the existing matrix melt crystal mush and for the extreme enrichment of some ore forming elements highly soluble in alkali and water rich supercritical fluids a very important point in mineral crystallization is the non uniform local enrichment of rare and economically significant elements at specific locations in pegmatites granites and other rocks given the properties of the supercritical phase identified from melt inclusions the process of ostwald ripening can operate very effectively the driving force for ostwald ripening arises because the concentration of solute in the vicinity of small crystals or clusters is greater than and in the vicinity of larger crystals or clusters less than the average supersaturation the solute in the supercritical fluid therefore flows from the small crystals to the larger crystals and permits the growth of very large crystals at the expense of smaller ones this is favored by the extraordinary properties of supercritical fluids given the low surface tension the supercritical fluid can move also through grain boundaries and small channels or dislocation pipes aiding incompatible element transport additionally their consequences for the formation of some important granite related ore deposits are briefly outlined

trace element geochemistry by laser ablation icp ms of micas associated with ta mineralization in the tanco pegmatite manitoba canada in the tanco pegmatite one of the world s major ta deposits tantalum mineralization shows a complexity that reflects the complex petrogenesis of its host pegmatite micas are common in most of the pegmatite units and are intimately associated with the successive stages of ta mineralization from the wall zone to the central zones where micaceous replacement is pervasive different generations of micas both primary and secondary associated with ta oxides were selected for electron microprobe and laser ablation icp ms investigation their chemical trends are used to constrain the magmatic versus hydrothermal processes that played a role in their crystallization and their associated ta mineralization micas range from dioctahedral muscovite to trioctahedral lepidolite through al li substitution unexpectedly the most evolved compositions low k rb ratios and high li contents occur in the wall zone they are interpreted to reflect nonequilibrium crystallization from an undercooled melt with or without boundary layer effects in the central zones the fine grained mica quartz assemblage hosts some coarser grained li muscovite which has the highest ta contents up to 400 ppm these li f a rich micas are interpreted to originate from a magmatic metasomatic event which was also at the origin of the mqm style ta mineralization at tanco however the li ta poor muscovite end member compositions of fine grained alteration micas suggest crystallization from an aqueous fluid during a metasomatic hydrothermal event involving late pegmatitic fluids the low ta concentrations around 50 ppm of this fine grained muscovite suggest that this fluid transported at least small amounts of ta

nb ta fractionation in peraluminous granites a marker of the magmatic hydrothermal transition in their late stages of evolution peraluminous granitic melts exsolve large amounts of fluidswhich can modify the chemical composition of granitic whole rock samples the niobium tantalum nb ta ratio is expected to decrease during the magmatic differentiation of graniticmelts but the behavior of both elements at the magmatic hydrothermal transition remainsunclear using a compilation of whole rock geochemical data available in the literature wedemonstrate that fractional crystallization alone is not sufficient to explain the distribution ofnb ta in most peraluminous granites however we notice that most of the granitic samplesdisplaying evidence of interactions with fluids have nb ta 5 we propose that the decreaseof the nb ta ratio in evolved melts is the consequence of both fractional crystallization andsub solidus hydrothermal alteration we suggest that the nb ta value of 5 fingerprints themagmatic hydrothermal transition in peraluminous granites furthermore a nb ta ratio of 5appears to be a good marker to discriminate mineralized from barren peraluminous granites

modeling of the thermohydromechanical chemical response of ontario sedimentary rocks to future glaciations in this work the response of a proposed deep geological repository dgr located in sedimentary rock formations of southern ontario to potential future glaciation cycles is investigated numerica

conceptualising and mapping coupled estuary coast and inner shelf sediment systems whilst understanding and predicting the effects of coastal change are primarily modelling problems it is essential that we have appropriate conceptual frameworks for 1 the formalisation of existing knowledge 2 the formulation of relevant scientific questions and management issues 3 the implementation and deployment of predictive models and 4 meaningful engagement involvement of stakeholders important progress continues to be made on the modelling front but our conceptual frameworks have not evolved at a similar pace accordingly this paper presents a new approach that re engages with formal systems analysis and provides a mesoscale geomorphological context within which the coastal management challenges of the 21st century can be more effectively addressed coastal and estuarine system mapping cesm is founded on an ontology of landforms and human interventions that is partly inspired by the coastal tract concept and its temporal hierarchy of sediment sharing systems but places greater emphasis on a hierarchy of spatial scales this extends from coastal regions through landform complexes to landforms the morphological adjustment of which is constrained by diverse forms of human intervention crucially cesm integrates open coastal environments with estuaries and relevant portions of the inner shelf that have previously been treated separately in contrast to the nesting of littoral cells that has hitherto framed shoreline management planning cesm charts a complex web of interactions of which a sub set of mass transfer pathways defines the sediment budget and a multitude of human interventions constrains natural landform behaviour conducted within a geospatial framework cesm constitutes a form of knowledge formalisation in which disparate sources of information published research imagery mapping raw data etc are generalised into usable knowledge the resulting system maps provide a framework for the development and application of predictive models and a repository for the outputs they generate not least flux estimates for the major sediment system pathways they also permit comparative analyses of the relative abundance of landforms and the multi scale interactions between them finally they articulate scientific understanding of the structure and function of complex geomorphological systems in a way that is transparent and accessible to diverse stakeholder audiences as our models of mesoscale landform evolution increase in sophistication cesm provides a platform for a more participatory approach to their application to coastal and estuarine management

magmatic hydrothermal rare element mineralization in the songshugang granite northeastern jiangxi china insights from an electron microprobe study of nb ta zr minerals abstract the songshugang granite hidden in the sinian metasedimentary stratum is a highly evolved rare element granite in northeastern jiangxi province south china the samples were systematically taken from the ck 102 drill hole at the depth of 171 423 m four types of rocks were divided from the bottom upwards topaz albite granite as the main body greisen nodules topaz k feldspar granite and pegmatite layer electron microprobe study reveals that the rare element minerals of the songshugang granite are very different from those of other rare element granites mn mn fe mn and ta ta nb ta of columbite group minerals and hf hf zr hf of zircon are nearly constant within each type of rocks however back scattered electron imaging revealed that nb ta oxides and zircon of the songshugang granite especially those of topaz albite granite topaz k feldspar granite and greisen are commonly characterized by a specific two stage texture on the crystal scale the early stage nb ta oxide is simply subhedral shaped columbite fe cgm i with low mn 0 16 0 37 and ta 0 05 0 29 columbite fe is penetrated by the later stage tantalite veinlets cgm ii or surrounded by complex nb ta sn w mineral assemblages including tantalite fe wodginite sl cassiterite and ferberite tantalite has wide range of mn values 0 15 0 88 from fe dominance to mn dominance wodginite with ta nb has large variable concentrations of w sn and ti cassiterite and ferberite are all enriched in nb and ta nb 2 o 5 ta 2 o 5 up to 20 12 wt and 31 42 wt respectively with high ta 0 5 similar to nb ta oxides and nb ta sn w mineral assemblages the early stage zircon is commonly included by the later stage zircon with sharply boundary they have contrasting hf contents and hfo 2 of the later stage zircon is up to 28 13 wt petrographic features indicate that the early stage of columbite and zircon were formed in magmatic environment however the later stage of rare element minerals were influenced by fluxes enriched fluids tantalite together with wodginite cassiterite and ferberite implies a ta dominant media an interstitial fluid rich melt enriched in ta and flux at the magmatic hydrothermal transitional stage is currently a favored model for explaining the later stage of rare element mineralization

the impact of sea level rise and climate change on inshore wave climate a case study for east anglia uk in coastal areas offshore wave propagation towards the shore is influenced by water depth variations due to sea bed bathymetry tides and surges considering implications of climate change both on atmospheric forcing and sea level rise a simple methodology involving numerical modelling is implemented to compute inshore waves from 1960 to 2099 simulations take into account five scenarios of linear sea level rise and one climatic scenario for storm surges and offshore waves the methodology is applied to the east anglia coast uk extreme event analysis is performed to estimate climate change implication on inshore waves and the occurrence of extreme events it is shown for this coastal region that wave statistics are sensitive to the trend in sea level rise and that the climate change scenario leads to a significant increase of extreme wave heights in the northern part of the domain for nearshore points the increase of the mean sea level alters not only extreme wave heights but also the frequency of occurrence of extreme wave conditions

photoelastic and numerical investigation of stress distributions around fault models under biaxial compressive loading conditions abstract this paper presents the results of a photoelastic and numerical study of stress distributions contours and trajectories around fault models of various geometries submitted to a biaxial compressive load it aims to describe typical biaxial stress behaviours and emphasize the existing differences with the well known uniaxial compressive load case stress trajectories are sometimes shown by joint sets acting as markers of a paleostress field and they can be interpreted by particular shallow tension compression situations at depth fractures can be reactivated or can dilate under conditions of triaxial compression and behaviour is essentially controlled by a high stress ratio high 3 1 ratio in spite of the potential importance of such stress states on fracture permeability and fluid flow and although they are frequently found at depth in a reservoir context such stress conditions are poorly investigated particularly in terms of stress perturbations the presented analogue experiments consisted of compression tests done on polymethylmethacrylate pmma plates this material has mechanical properties comparable to those of brittle rocks in the upper crust and presents birefringence the samples contained open defects acting as faults and the stress trajectories around these faults were investigated using a photoelastic device comparable numerical experiments were realised with a finite element code franc 2d using frictionless fault models first the effect of an increasing biaxial compressive load ratio 3 1 on stress trajectories around an isolated open defect was explored it was shown that the stress trajectories were drastically modified when 3 1 increased from 0 2 to 0 4 this result being consistent with previous studies in particular when 3 1 was superior or equal to 0 4 external isotropic points around where trajectories diverged called repulsive isotropic points appeared near the tips but away from the defects they tended to move away from the defects towards the main load direction when 3 1 increased the described isotropic points were points of stress trajectory divergence i e points where stress decreased implying that zones around them were strongly unfavourable to shear reactivation second stress trajectories around fault models of various geometries oblique isolated defect dilational jog compressive jog and complex patterns were studied the applied biaxial compressive load ratio being 0 7 these biaxial stress trajectories were compared with similar uniaxial stress trajectories in order to explore the existing differences between the two regimes it enabled new stress trajectory geometries to be described and interpreted in particular numerous external repulsive isotropic points were observed and defect tips were shown to be zones of high convergence of stress trajectories furthermore in contrast to the uniaxial compressive load case stress trajectories and stress contours were geometrically similar within dilational and compressive jogs under biaxial compressive load for both jog types the centre of the overlapping zone and the areas along the wall of a jog defining fault and facing the overlapping tip of the other fault proved to be zones of low mean stress implying that fluids may migrate towards them from the tips of the faults in response to mean stress gradients furthermore the centre of the jogs exhibiting a high differential stress was a favourable area in terms of fracture reactivation which may facilitate fluids transfer and storage it was also observed that for both the uniaxial and biaxial compressive loads isotropic zones were localised at the acute angle between branching defects

southern north sea storm surge event of 5 december 2013 water levels waves and coastal impacts the storm surge event that affected the coastal margins of the southern north sea on 5 6 december 2013 produced the highest still water levels on record at several tide gauges on the uk east coast on east facing coasts south of the humber estuary and north facing norfolk water levels were higher than in the twentieth century benchmark surge event of 31 january 1 february 1953 maximum significant wave heights were highest off the north norfolk coast peak hs 3 8 m offshore 2 9 m inshore and lowest off the suffolk coast hs 1 5 1 8 m inshore comparable offshore wave heights in 1953 were 7 8 m and ca 3 m the lower wave heights and their short duration in 2013 explain both localised breaching overtopping and back barrier flooding associated with gravel ridges and relatively low earthen banks as well as the lack of failure in more highly engineered coastal defences on barrier coasts and within estuaries the signal of maximum runup was highly variable reflecting the modification of the tide surge wave signal by inshore bathymetry and the presence of a range of coastal ecosystems the landscape impacts of the december 2013 surge included the notching of soft rock cliffs and cliffline retreat erosion of coastal dunes and the augmentation or re activation of barrier island washover deposits whilst surge event related cliff retreat on the rapidly eroding cliffs of the suffolk coast lay within the natural variability in inter annual rates of retreat the impact of the surge on upper beach sand dune margins produced a pulse of shoreline translation landwards equivalent to about 10 years of normal shoreline retreat the study of east coast surges over the last 60 years and the identification of significant phases of landscape change such as periods of rapid soft rock cliff retreat and the formation of new gravel washovers on barrier islands points to the importance of high water levels being accompanied by high wave activity future developments in early warning systems and evacuation planning require information on the variable impacts of such extreme events

a 150 year record of coastline dynamics within a sediment cell eastern england abstract coastal sediment cells reflect processes operating at a range of scales but it is the medium spatial and temporal scales decades to centuries that are of greatest interest for coastal management this paper focuses on coastline position change within a single sediment cell over 150 years where the geomorphology includes cliffs beaches and saltmarshes the focus is the east coast of england from flamborough head to gibraltar point although the updrift sector of this sediment cell has been studied for well over a century the downdrift sector has attracted significantly less attention using topographic profiles bathymetric profiles aerial photographs and historical maps we mapped coastline erosion and accretion using the digital shoreline analysis system dsas and calculated volumetric changes for different morphometric units rapid erosion of the updrift holderness cliffs has been counterbalanced with accretion on beaches along the downdrift lincolnshire coast the amount of accretion in lincolnshire corresponds to around 29 of the volume of sediment eroded from holderness much of the eroded cliff material is likely to be deposited temporarily into nearshore and offshore sand banks before being redistributed by cross shore currents an exploration of storm surge impact on long term erosion and accretion rates showed no clear relationship between storm surge frequency and change in coastline position however this may be in part due to the relative timing of storm occurrence and data acquisition the jenkinson daily weather type classification was found to be a reasonable proxy for the occurrence of strong onshore winds which may offer scope for further investigation of the role of forcing factors over time periods beyond the length of the meteorological and tidal station records winter north atlantic oscillation phase was not a good indicator of storminess on the east coast of england but may be a useful proxy for quiescence

numerical methods in rock mechanics the purpose of this civilzone review paper is to present the techniques advances problems and likely future development directions in numerical modelling for rock mechanics and rock engineering

fault zone weakening and character of slip along low angle normal faults insights from the zuccale fault elba italy a seismically active low angle normal fault is recognized at depth in the northern apennines italy where recent exhumation has also exposed ancient examples at the surface notably the zuccale fault on elba field based and microstructural studies of the zuccale fault reveal that an initial phase of pervasive cataclasis increased fault zone permeability promoting influx of co 2 rich hydrous fluids this triggered low grade alteration and the onset of stress induced dissolution precipitation processes e g pressure solution as the dominant grain scale deformation process in the pre existing cataclasites leading to shear localization and the formation of a narrow foliated fault core dominated by fine grained hydrous mineral phases these rocks exhibit ductile deformation textures very similar to those formed during pressure solution accommodated frictional viscous creep in experimental fault rock analogues the presence of multiple hydrofracture sets also points to the local attainment of fluid overpressures following development of the foliated fault core which significantly enhanced the sealing capacity of the fault zone a slip model for low angle normal faults in the apennines is proposed in which aseismic frictional viscous creep occurs on a weak slow moving slip rate 1 fault interspersed with small seismic ruptures caused by cyclic hydrofracturing events our findings are potentially applicable to other examples of low angle normal faults in many tectonic settings

fractionation trends in mica and tourmaline as indicators of pegmatite internal evolution bob ingersoll pegmatite black hills south dakota abstract pegmatitic micas from the bob ingersoll no 1 dike a large internally zoned rare element pegmatite body have been analyzed for trends of compositional variation that indicate the sequence of crystallization and record the progressive compositional differentiation of the pegmatite the dike consists of six primary zones and one replacement assemblage 2m 1 muscovite occurs in the border and wall zones and outer parts of the first intermediate zone intermediate li micas of mixed polytype but with a dominant 2m 1 component occur in inner parts of the pegmatite including the core and areas of contact between intermediate zones and the core 2m 2 lepidolite occurs as a replacement of k feldspar along margins between the first intermediate zone and core fractionation trends of the micas include increasing li substitution decreasing rb cs and increasing ta nb ta in a general sequence from the outer wall zone to the pegmatite core but with considerable overlap among intermediate zones when compared to coexisting tourmaline overlapping compositional trends of the interior zones suggest overlap in timing of crystallization and interzonal geochemical communication border zone mineral compositions do not fit major variation trends due to the combined effects of wallrock contamination replacement of early microcline by lithian mica during differentiation of the pegmatite and possibly rapid disequilibrium crystallization strong zoning of mica and tourmaline crystals reflects disequilibrium conditions as crystalline pegmatite reacted with compositionally evolving fluids lithian mica and lepidolite that replaced early formed k feldspar may have been generated by fluids that were in equilibrium with a residual silicate melt in the pegmatite core aqueous fluids exsolved from silicate melt appear to have leaked from the pegmatite throughout much of its crystallization history and the late stage li rb and cs enriched fluids contributed to the exomorphic halo surrounding the pegmatite

geomechanical model of the marmara sea region i 3 d contemporary kinematics summary we investigate by means of a 3 d geomechanical model the relationship between structural elements and contemporary kinematics in the marmara sea region northwest turkey the recently imaged fault system beneath the marmara sea is incorporated into the model as frictional surfaces with varying strike and dip the main marmara fault is implemented as through going and is accompanied by mostly non vertical second order faults topography basement topography and the moho become mechanically effective through changes in density and elastic parameters across these horizons the model is subjected to gravity and kinematic boundary conditions the ultimate goal of this study is to set up a 3 d model that is consistent with both kinematic observations and stress data the stress results are presented in a complementary paper in this paper we present the modelled long term 3 d kinematics in terms of fault slip rates rotations vertical motion and sense of fault slip the model results agree with global positioning system velocities geological fault slip rates palaeomagnetic measurements and with the observed pattern of subsidence and uplift furthermore our tectonically driven vertical velocities can be linked to landscape and basin evolution and to features of sedimentation our results indicate that the main marmara fault can be interpreted as a through going fault that slips almost purely in a strike slip sense nevertheless and not contradictory to the previous statement there is significant dip slip motion at some sections of the main marmara fault the agreement of the modelled 3 d kinematics with model independent observations supports that the main structural details of the fault system are accounted for sensitivity analysis of model parameters reveals that changes in rock properties and the initial stress state have minor influence on the 3 d kinematics we conclude that the 3 d structure of the fault system is the key control of the kinematics the slip rate of the main marmara fault from our model is lower than previous estimates and shows high variability along strike 12 8 17 8 mm a 1 the latter indicates that stress accumulation is non uniform along strike

columbite solubility in granitic melts consequences for the enrichment and fractionation of nb and ta in the earth s crust the behaviour of niobium and tantalum in magmatic processes has been investigated by conducting mnnb2o6 and mnta2o6 solubility experiments in nominally dry to water saturated peralkaline aluminium saturation index a s i 0 64 to peraluminous a s i 1 22 granitic melts at 800 to 1035 c and 800 to 5000 bars the attainment of equilibrium is demonstrated by the concurrence of the solubility products from dissolution crystallization mn doped and nb or ta doped experiments at the same pressure and temperature the solubility products of mnnb2o6 ksp nb and mnta2o6 ksp ta at 800 c and 2 kbar both increase dramatically with alkali contents in water saturated peralkaline melts they range from 1 2 10 4 and 2 6 10 4 mol2 kg2 respectively in subaluminous melt a s i 1 02 to 202 10 4 and 255 10 4 mol2 kg2 respectively in peralkaline melt a s i 0 64 this increase from the subaluminous composition can be explained by five non bridging oxygens being required for each excess atom of nb5 or ta5 that is dissolved into the melt the ksp nb and ksp ta also increase weakly with al content in peraluminous melts ranging up to 1 7 10 4 and 4 6 10 4 mol2 kg2 respectively in the a s i 1 22 composition columbite tantalite solubilities in subaluminous and peraluminous melts a s i 1 02 and 1 22 are strongly temperature dependent increasing by a factor of 10 to 20 from 800 to 1035 c by contrast columbite tantalite solubility in the peralkaline composition a s i 0 64 is only weakly temperature dependent increasing by a factor of less than 3 over the same temperature range similarly ksp nb and ksp ta increase by more than two orders of magnitude with the first 3 wt h2o added to the a s i 1 02 and 1 22 compositions whereas there is no detectable change in solubility for the a s i 0 64 composition over the same range of water contents solubilities are only slightly dependent on pressure over the range 800 to 5000 bars the data for water saturated sub and peraluminous granites have been extrapolated to 600 c conditions at which pegmatites and highly evolved granites may crystallize using a melt concentration of 0 05 wt mno 70 to 100 ppm nb or 500 to 1400 ppm ta are required for manganocolumbite and manganotantalite saturation respectively the solubility data are also used to model the fractionation of nb and ta between rutile and silicate melts predicted rutile melt partition coefficients increase by about two orders of magnitude from peralkaline to peraluminous granitic compositions it is demonstrated that the nb2o5 ta2o5 activity coefficient ratio in the melt phase depends on melt composition this ratio is estimated to decrease by a factor of 4 to 5 from andesitic to peraluminous granitic melt compositions accordingly all the relevant accessory phases in subaluminous to peraluminous granites are predicted to incorporate nb preferentially over ta this explains the enrichment of ta over nb observed in highly fractionated granitic rocks and in the continental crust in general

a predictive mesoscale model of the erosion and profile development of soft rock shores the development application and behaviour of a generic model of retreating soft rock e g clay shores is described this represents a broad system in coastal modelling terms comprising shore platform beach tidal range wave transformation cliff and talus the coast is divided into a series of representative cross shore profiles each of which is discretised into a column of elements erosion of a platform element at each timestep depends on its gradient material strength is dealt with as a calibration constant wave forces are averaged over durations of a tide or hour and sediment transport is represented in bulk terms attention has been focussed on interaction between system parts and the emergence of system properties in particular profile shape this is allowed to develop towards dynamic equilibrium and is the principal means of model validation the emergence of the profile shape is dominated by the distribution of wave scour by the tide and by interaction with a beach if present because the model is process based it may be used to model the effects of climate change and engineering intervention yet it is also computationally inexpensive so may be used to explore uncertainty through probabilistic application the breadth of the included system coupled with short run times enables predictions over timescales of decades which we refer to as the mesoscale the model is used to explore the dynamics of retreating soft rock shore profiles and to predict future behaviour of a study site

high resolution downscaled ocean waves dow reanalysis in coastal areas abstract large scale wave reanalysis databases 0 1 1 spatial resolution provide valuable information for wave climate research and ocean applications which require long term time series 20 years of hourly sea state parameters however coastal studies need a more detailed spatial resolution 50 500 m including wave transformation processes in shallow waters this specific problem called downscaling is usually solved applying a dynamical approach by means of numerical wave propagation models requiring a high computational time effort besides the use of atmospheric reanalysis and wave generation and propagation numerical models introduce some uncertainties and errors that must be dealt with in this work we present a global framework to downscale wave reanalysis to coastal areas taking into account the correction of open sea significant wave height directional calibration and drastically reducing the cpu time effort about 1000 by using a hybrid methodology which combines numerical models dynamical downscaling and mathematical tools statistical downscaling the spatial wave variability along the boundaries of the propagation domain and the simultaneous wind fields are taking into account in the numerical propagations to performance similarly to the dynamical downscaling approach the principal component analysis is applied to the model forcings to reduce the data dimension simplifying the selection of a subset of numerical simulations and the definition of the wave transfer function which incorporates the dependency of the wave spatial variability and the non uniform wind forcings the methodology has been tested in a case study on the northern coast of spain and validated using shallow water buoys confirming a good reproduction of the hourly time series structure and the different statistical parameters

textural and chemical variations of micas as indicators for tungsten mineralization evidence from highly evolved granites in the dahutang tungsten deposit south china

carboniferous triassic subduction and accretion in the western kunlun china implications for the collisional and accretionary tectonics of the northern tibetan plateau a newly defined 250 km by 500 km carboniferous triassic subduction accretion complex the mazar accretionary prism in the western kunlun comprises two subduction complexes and a forearc basin succession 1 the bazar dara subduction complex contains imbricated blocks of sandstone arenite limestone and metavolcanic rocks in a matrix of weakly metamorphosed triassic deep sea turbidites the metavolcanic rocks include basalt diabase spilite and andesitic porphyry trace element geochemistry shows that pillow and amygdaloidal basalts are oceanic island tholeiites this zone has ordovician to permian fossils and is situated on the older more highly deformed and metamorphosed side of the prism adjacent to the sailiyak magmatic arc 2 the heweitan subduction complex is composed of blocks of limestone turbidite and radiolarite in a slate phyllite matrix intercalated with calc alkalic volcanic rocks this complex has permian to triassic fossils and is situated on the younger less deformed and metamorphosed side of the prism adjacent to the suture zone 3 the qitai forearc basins are infilled with turbidites late triassic intercalated with carbonates these rocks overlie the accretionary prism the accretion related structure is dominated by large scale northeast dipping thrusts and subvertical cleavage stitched by 215 190 ma granites there is an overall decrease in metamorphic grade and deformation intensity from the arc to the suture zone across the bazar dara and heweitan subduction complexes the mazar accretionary prism formed by subduction accretion processes during closure of the paleotethyan ocean and the final docking of the gondwanan karakoram qiangtang block to the cathaysian eurasian kunlun block

stress orientations of taiwan chelungpu fault drilling project tcdp hole a as observed from geophysical logs 1 the taiwan chelungpu fault drilling project tcdp drilled a 2 km deep research borehole to investigate the structure and mechanics of the chelungpu fault that ruptured in the 1999 mw 7 6 chi chi earthquake geophysical logs of the tcdp were carried out over depths of 500 1900 m including dipole sonic imager dsi logs and formation micro imager fmi logs in order to identify bedding planes fractures and shear zones from the continuous core obtained from the borehole a shear zone at a depth of 1110 meters is interpreted to be the chelungpu fault located within the chinshui shale which extends from 1013 to 1300 meters depth stress induced borehole breakouts were observed over nearly the entire length of the wellbore these data show an overall stress direction n115e that is essentially parallel to the regional stress field and parallel to the convergence direction of the philippine sea plate with respect to the eurasian plate variability in the average stress direction is seen at various depths in particular there is a major stress orientation anomaly in the vicinity of the chelungpu fault abrupt stress rotations at depths of 1000 m and 1310 m are close to the chinshui shale s upper and lower boundaries suggesting the possibility that bedding plane slip occurred during the chi chi earthquake citation wu h y k f ma m zoback n boness h ito j h hung and s hickman 2007 stress orientations of taiwan chelungpu fault drilling project tcdp hole a as observed from geophysical logs geophys res lett 34 l01303 doi 10 1029 2006gl028050

numerical modelling of fault reactivation in carbonate rocks under fluid depletion conditions 2d generic models with a small isolated fault abstract this generic 2d elastic plastic modelling investigated the reactivation of a small isolated and critically stressed fault in carbonate rocks at a reservoir depth level for fluid depletion and normal faulting stress conditions the model properties and boundary conditions are based on field and laboratory experimental data from a carbonate reservoir the results show that a pore pressure perturbation of 25 mpa by depletion can lead to the reactivation of the fault and parts of the surrounding damage zones producing normal faulting downthrows and strain localization the mechanism triggering fault reactivation in a carbonate field is the increase of shear stresses with pore pressure reduction due to the decrease of the absolute horizontal stress which leads to an expanded mohr s circle and mechanical failure consistent with the predictions of previous poroelastic models two scenarios for fault and damage zone permeability development are explored 1 large permeability enhancement of a sealing fault upon reactivation and 2 fault and damage zone permeability development governed by effective mean stress in the first scenario the fault becomes highly permeable to across and along fault fluid transport removing local pore pressure highs lows arising from the presence of the initially sealing fault in the second scenario reactivation induces small permeability enhancement in the fault and parts of damage zones followed by small post reactivation permeability reduction such permeability changes do not appear to change the original flow capacity of the fault or modify the fluid flow velocity fields dramatically

experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite we present an experimental study of synthetic peraluminous granite doped with h2o b p and f which confirms that aluminosilicate melt hydrous fluid and hydrosaline melt high temperature brine can stably coexist at 450 900 c and 0 1 0 2 gpa in bulk compositions similar to those of natural granitic pegmatites hydrosaline melt is not quenchable unstable at room conditions and requires special techniques for synthesis and preservation raman spectroscopy and electron microprobe analyses of hydrosaline melt synthesized in our experiments show that it is composed of h3bo3 na3alf6 alpo4 h2o and aluminosilicate components aluminosilicate melt saturated in both hydrosaline liquid and hydrous fluid at 850 c and 0 2 gpa contains 3 6 wt f 4 2 wt p2o5 and 4 wt b2o3 natural hydrosaline melts have previously been found as inclusions trapped in rock forming minerals they are not restricted to granites and can be effective agents for enhanced crystal growth metasomatism and ore formation in addition hydrosaline melts may account for many characteristic features of rare element and miarolitic pegmatites such as giant size and perfect shapes of crystals in pegmatite cores diverse mineralogy and strong enrichment in rare elements

a comparison of extreme wave analysis methods with 1994 2010 offshore perth dataset abstract this study took the hourly wave height records collected 10 km southwest of rottnest island offshore of perth western australia from 1994 to 2010 as a testing ground and compared the results obtained by the goda method commonly used in costal engineering community the generalised extreme value gev and generalised pareto distribution gpd methods which are currently the standard practice in mainstream extreme statistics the results highlight the merits and limitations associated with those methods and formulas it is recommended that the coastal engineering community should embrace the gpd distribution as one of the credible candidates due to its merits in the threshold selection techniques and the nature of the distribution the conventional distributions recommended by goda could be the other candidates provided a properly selected threshold value the final selection of the distributions should be made based on the goodness of fit test demonstrated in this study finally the extreme wave heights for offshore perth are recommended based on 1994 to 2010 dataset

a novel approach to model earth fissure caused by extensive aquifer exploitation and its application to the wuxi case china initially observed in the semi arid basins of southwestern usa earth fissures due to aquifer over exploitation are presently threatening a large number of subsiding basins in various countries worldwide different mechanics have been proposed to explain this process such as differential compaction horizontal movements and fault reactivation numerical modeling and prediction of this major geo hazard caused by overuse of groundwater resources are challenging because of two main requirements shifting from the classical continuous to discontinuous geomechanics and incorporating 2 dimensional features the earth fissures into large 3 dimensional 3d modeling domain the subsiding basin in this work we proposed a novel modeling approach to simulate earth fissure generation and propagation in 3d complex geological settings a nested two scale approach associated with an original non linear elasto plastic finite element interface element simulator allows modeling the mechanics of earth discontinuities in terms of both sliding and opening the model is applied on a case study in wuxi china where groundwater pumping between 1985 and 2004 has caused land subsidence larger than 2 m the model outcomes highlight that the presence of a shallow 80 m deep bedrock ridge crossing the yangtze river delta is the key factor triggering the earth fissure development in this area bending of the alluvial deposits around the ridge tip and shear stress due to the uneven piezometric change and asymmetrical shape of the bedrock have caused the earth fissure to onset at the land surface and propagate downward to a maximum depth of about 20 30 m maximum sliding and opening are computed in the range of 10 to 40 cm in agreement with the order of magnitude estimated in the field

alkali metal and rare earth element evolution of rock forming minerals from the gatumba area pegmatites rwanda quantitative assessment of crystal melt fractionation in the regional zonation of pegmatite groups abstract this study presents a general model for the evaluation of rayleigh fractional crystallisation as the principal differentiation mechanism in the formation of regionally zoned common and rare element pegmatites the magmatic evolution of these systems from a granitic source is reconstructed by means of alkali element and rare earth element ree analyses of rock forming minerals feldspars micas and tourmaline which represent a whole sequence of regional pegmatite zonation the gatumba pegmatite field rwanda central africa is chosen as case study area because of its well developed regional zonation sequence the pegmatites are spatially and temporally related to peraluminous g4 granites 986 10 ma the regional zonation is developed around a g4 granite and the proximal pegmatites grade outwardly into biotite two mica and muscovite pegmatites rare element nb ta sn pegmatites occur most distal from the granite alkali metal fractionation trends in pegmatitic k feldspar rb 350 6000 ppm cs 2 160 ppm and muscovite rb 670 7000 ppm cs 10 150 ppm define a single and continuous trend which is modelled by rayleigh fractional crystallisation starting from a parental granite composition g4 composition k 3 1 wt rb 222 ppm cs 11 ppm the fractionation model shows moreover that the pegmatites adjacent to the parental pluton are the least fractionated and the distal pegmatites are the most fractionated biotite pegmatites form from 0 to 69 crystallisation two mica pegmatites from 69 to 92 and muscovite pegmatites from 92 crystallisation onwards the extreme rb and cs enrichment in rare element pegmatites requires at least 98 fractionation of the initial g4 granite composition mathematical derivation of the k rb versus cs relationship in k feldspars confirms rayleigh fractional crystallisation as the main differentiation process in the development of regional pegmatite zonation moreover 1 it demonstrates the continuity of the fractionation process from biotite pegmatites to rare element pegmatite and indicates a genetic link among them and 2 it allows a general evaluation of pegmatite fields in terms of system parameters i e the initial element concentration in the granitic melt and partition coefficients ree patterns of the rock forming minerals feldspars muscovite biotite and schorl show a distinct transition along the regional zonation they evolve from sloping fractionated to more flat patterns starting from the biotite up to the muscovite pegmatites minerals from the rare element pegmatites feldspars muscovite and elbaite show again more fractionated heavy ree depleted patterns the observed evolution in the ree patterns corresponds to early crystallisation of light ree enriched monazite and a late crystallisation of mainly cogenetic heavy ree enriched phases such as apatite columbite group minerals and beryl modelling of rayleigh fractionation starting from an initial parental granite g4 composition lan ybn 10 and ree 83 shows that this evolution in mineral ree pattern is the result of fractional crystallisation of the pegmatitic melt and precipitation of ree incorporating minerals such as monazite and apatite consequently trace element modelling indicates that rayleigh fractional crystallisation governs the mineralogical and geochemical evolution from a granite source to common and eventually rare element pegmatites this mechanism shows that granitic pegmatites are extremely fractionated residual melts which are genetically and directly connected to a main granite body

structural geometry of raplee ridge monocline and thrust fault imaged using inverse boundary element modeling and alsm data abstract we model the raplee ridge monocline in southwest utah where airborne laser swath mapping alsm topographic data define the geometry of exposed marker layers within this fold the spatial extent of five surfaces were mapped using the alsm data elevations were extracted from the topography and points on these surfaces were used to infer the underlying fault geometry and remote strain conditions first we compare elevations extracted from the alsm data to the publicly available national elevation dataset 10 m dem digital elevation model ned 10 and 30 m dem ned 30 while the spatial resolution of the ned datasets was too coarse to locate the surfaces accurately the elevations extracted at points spaced 50 m apart from each mapped surface yield similar values to the alsm data next we used a boundary element model bem to infer the geometry of the underlying fault and the remote strain tensor that is most consistent with the deformation recorded by strata exposed within the fold using a bayesian sampling method we assess the uncertainties within and covariation between the fault geometric parameters and remote strain tensor inferred using the model we apply these methods to the raplee ridge monocline and find that the resolution and precision of the alsm data are unnecessary for inferring the fault geometry and remote strain tensor using our approach however the alsm data were necessary for the mapping of the spatial distribution of surface outcrops our models considered two scenarios one in which fault geometry and remote strains were inferred using a single deformed stratum and another in which all mapped strata were used in the inversion modeled elevations match those observed to within a root mean squared error of 16 18 m and show little bias with position along the fold both single and multilayer inversions image a fault that is broadly constrained to be 4 5 14 km in down dip height 13 30 km in along strike width with a tip line 2 0 9 5 km below the surface at the time of deformation poisson s ratio was not well resolved by the inversion the idealized elastic model is oversimplified when considering the complicated layered nature of this fold however it provides a good fit to the observations thus comparable surface displacements may be produced with a variety of rheological models so independent constraints on factors such as the fault geometry may be required to ascertain the appropriate rheology of the fold

field evidences for the role of static friction on fracture orientation in extensional relays along strike slip faults comparison with photoelasticity and 3 d numerical modeling fault friction is a parameter that is difficult to assess along fault zones since its determination depends on the knowledge of any factor controlling the state of stress around faults in brittle homogeneous rocks a limited number of these factors such as the shape of the fault surface the vicinity of fault tips or the remote stress ratio are crucial to constrain for this determination in this paper we propose to analyse a field example in which all these properties are met and where the nature of the slipped structure suggest differences in static friction we compare the orientations of branching fractures at strike slip relay zones between en echelon stylolites and en echelon joints both reactivated in shear the field data are compared with both photoelastic and 3 d numerical models that consider the remote stress conditions and the role of the geometry of the strike slip segments based on field observations these analyses quantitatively demonstrate the significant role of fault friction on the local stress field orientation and subsequent fracture formation this work points out that estimations of fault friction based on analyses of fracture patterns or in situ stresses must be accompanied with a thorough investigation of the 3 d fault shape its segmentation and the remote stress state

morphodynamic behaviour of a nearshore sandbank system the great yarmouth sandbanks u k offshore sandbanks provide a major source of sediment and may have a significant impact on the evolution of the nearby shoreline the prediction of sandbank evolution is extremely important for coastal engineers and managers however it is evident from the existing literature that additional investigations into the evolution of offshore sandbanks are needed the present paper describes qualitative and quantitative investigations of the evolution of the great yarmouth sandbanks a depth integrated tidal model has been used to calculate the residual currents arising from the sequence of sandbank configurations observed from historic charts over a 150 year period tidal simulations were performed with a nested model covering the southern north sea and great yarmouth zone east coast of the uk simulations were carried out for a period corresponding to several spring neap cycles to calculate residual currents and were compared directly with field measurements model calibration and validation was performed against published tidal elevation charts based on many observations tidal predictions and field measurements these detailed comparisons have been used to determine the errors in the model predictions overall the performance of the model is considered good the model output has been analysed to investigate qualitative links between the sandbank configuration and the residual flow statistics the results demonstrate that the long term changes in sandbank morphology can be explained from the pattern of tidal residual currents

immiscibility between silicate magmas and aqueous fluids a melt inclusion pursuit into the magmatic hydrothermal transition in the omsukchan granite ne russia abstract exsolution unmixing of the volatile element rich phases from cooling and crystallising silicate magmas is critical for element transport from the earth s interior into the atmosphere hydrosphere crustal hydrothermal systems and the formation of orthomagmatic ore deposits unmixing is an inherently fugitive phenomenon and melt inclusions droplets of melt trapped by minerals provide robust evidence of this process in this study melt inclusions in phenocrystic and miarolitic quartz were studied to better understand immiscibility in the final stages of cooling of and volatile exsolution from granitic magmas using the tin bearing omsukchan granite ne russia as an example primary magmatic inclusions in quartz phenocrysts demonstrate the coexistence of silicate melt and magma derived cl rich fluids brine and vapour and emulsions of these during crystallisation of the granite magma microthermometric experiments in conjunction with pixe and other analytical techniques disclose extreme heterogeneity in the composition of the non silicate phases even in fluid globules within the same silicate melt inclusion we suggest that the observed variability is a consequence of strong chemical heterogeneity in the residual silicate melt brine vapour system on a local scale owing to crystallisation immiscibility and failure of individual phases to re equilibrate the possible evolution of non silicate volatile magmatic phases into more typical hydrothermal chloride solutions was examined using inclusions in quartz from associated miarolitic cavities

comparing different extreme wave analysis models for wave climate assessment along the italian coast abstract by utilizing various statistical models to quantify the return levels of extreme significant wave height this study seeks to achieve two objectives the updating of the state of the art concerning extreme wave analysis along the italian coast and the creation of a long term predictive model to these ends four different methods widely used in the field of metocean engineering are employed to analyze both buoy data rete ondametrica nazionale ron and wave data obtained by means of dynamical hindcasting techniques such as the forecast hindcast operational model chain in use at the university of genoa www dicca unige it meteocean return levels are estimated by the goda method the generalized extreme value gev and the generalized pareto distribution poisson point process models and the equivalent triangular storm ets algorithm all models follow the peak over threshold pot approach which require an optimal threshold implementation save for the gev analysis which is applied to model significant wave height maxima pertaining to time blocks the models exhibit different performance characteristics presented here and treated in depth in general noteworthy versatility characterizes the gpd poisson model which often recovers goda results while the gev and ets models exhibit limitations in assessment of a variety of wave fields greatly diversified in a semi closed basin such as the mediterranean sea long term estimates have been provided by means of the most appropriate model selected thus offering a complete overview of wave climate in the mediterranean basin based on wave hindcast data

formation of segmented normal faults a 3 d perspective the interpretation of fault kinematics from geometric data is an essential step in developing an understanding of the growth of fault systems constraints on fault geometry are however often restricted to 2 d maps or cross sections in this article we consider the extent to which kinematic interpretations of faulting benefit from a 3 d rather than 2 d geometrical perspective concentrating on relay zones and segmented normal fault arrays we suggest that very different interpretations of their evolution arise from the recognition that the propagation directions of faults and fault segments will rarely be contained within the inspection plane of 2 d data a 3 d perspective favours an interpretation in which the segments of a fault array are kinematically interrelated from their initiation individual segments in such systems may link into a single fault surface out of the plane of inspection or may be unconnected in 3 d we argue that this interpretation which conflicts with the often suggested model of incidental overlap of originally isolated faults should be the preferred model for the generation and growth of segmented normal fault arrays