the transition from peraluminous to peralkaline granitic melts evidence from melt inclusions and accessory minerals fractional crystallization of peraluminous f and h2o rich granite magmas progressively enriches the remaining melt with volatiles we show that at saturation the melt may separate into two immiscible conjugate melt fractions one of the fractions shows increasing peraluminosity and the other increasing peralkalinity these melt fractions also fractionate the incompatible elements to significantly different degrees coexisting melt fractions have differing chemical and physical properties and due to their high density and viscosity contrasts they will tend to separate readily from each other once separated each melt fraction evolves independently in response to changing t p x conditions and further immiscibility events may occur each generating its own conjugate pair of melt fractions the strongly peralkaline melt fractions in particular are very reactive and commonly react until equilibrium is attained consequently the peralkaline melt fraction is commonly preserved only in the isolated melt and mineral inclusions we demonstrate that the differences between melt fractions that can be seen most clearly in differing melt inclusion compositions are also visible in the composition of the resulting ore forming and accessory minerals and are visible on scales from a few micrometers to hundreds of meters

u pb dating of the madeira suite and structural control of the albite enriched granite at pitinga amazonia brazil evolution of the a type magmatism and implications for the genesis of the madeira sn ta nb ree cryolite world class deposit the madeira sn nb ta deposit corresponds to the albite enriched facies of madeira granite madeira suite that is part of a ne sw alignment of three granitic bodies structural analyses suggest that the albite enriched granite emplacement and development of related structures occurred in a different tectonic setting than earlier facies of the granitic bodies in the ne sw alignment and that the structure was dominated by a n ne trending shortening related to a left lateral motion along a ne sw corridor within a riedel shear three types of structures flat lying near vertical fractures and geodes miaroles concentrated the last magmatic related fluid in the albite enriched granite u pb in situ zircon dating of the albite enriched granite yielded an age of 1 822 22 ma the other granitic plutons of the madeira suite agua boa granite topaz granite facies and europa per alkaline granite formed at 1 825 14 ma 1 831 11 ma and 1 839 10 ma respectively the granite bodies of the madeira suite occur in an area occupied by a cauldron complex composed of volcanic sequences iricoume group and associated a type granites mapuera suite and their formation was controlled by the reactivation of the cauldron structures and the pre existing structures the gap between the cauldron complex and the madeira suite is no greater than 35 ma the geological evolution was reanalyzed from the perspective of an entire extensional environment where three successive episodes of a type magmatism and basin formation urupi formation occurred the data and interpretations of this work imply crucial constraints on the petrologic models proposed for the albite enriched granite and consequently on the genesis of the madeira deposit

evidence for aqueous liquid liquid immiscibility in highly evolved tin bearing granites mount pleasant new brunswick canada abstract three distinct types of fluid inclusions i e liquid vapor lv liquid vapor solid lvs and v only co exist within a single primary fluid inclusion assemblage in fluorite crystals that formed prior to and in close association with cassiterite mineralization in an assemblage comprising fluorite arsenopyrite topaz cassiterite in the sn w mo deposit of the north zone mount pleasant new brunswick the mineral assemblage occurs in vugs with late quartz and chlorite filling the remainder of the open space solid bearing inclusions contain up to eight optically different solids which are estimated to occupy up to approximately 70 vol of the fluid inclusions in a given fluid inclusion assemblage each type of fluid inclusion shows consistent l v or l v s phase ratios the results of microthermometric analyses show that lv inclusions have low salinities that vary from 0 to 10 wt nacl eq and homogenization temperatures that vary from 91 to 250 c within a given assemblage the ranges of salinity and homogenization temperatures of lv inclusions are even less in contrast co existing lvs inclusions are highly saline with salinities ranging from 36 to 40 wt nacl eq and have much higher homogenization temperatures that vary from 425 c to 600 c the upper limit of the microthermometric stage the salinity and homogenization temperature ranges of lvs inclusions show a limited range for a given assemblage the solids in lvs inclusions are interpreted as daughter phases due to consistent phase ratios in lvs fluid inclusions and because during heating experiments all solid phases melted prior to liquid vapor homogenization the consistency of phase ratios and the results of microthermometric analysis among lv or among lvs inclusions show that these inclusions were not formed through necking down of larger inclusions in addition the absence of sweat halos and re entrants rules out water loss as a possible mechanism for producing these coexisting fluid inclusions fluid inclusions of highly contrasting salinities and homogenization temperatures are therefore interpreted to be the result of trapping from two immiscible aqueous liquids it is unknown whether the two liquids exsolved from one single aqueous fluid or have different origins but consideration of the nature of inclusion assemblages in samples from other parts of the system suggest the latter topaz and cassiterite within the same mineral assemblage as well as late quartz contain lv fluid inclusion assemblages with microthermometric behaviors that are similar to the lv type inclusions in coexisting fluorite hosted lv and lvs inclusions suggesting that cassiterite deposited from the low salinity and temperature fluid

wave beach and dune interactions in southeastern australia abstract a morphodynamic classification of surfzones beaches and dunes of the microtidal low to high energy southeast australian coast is presented the first section a waves and beaches briefly deals with the transformation of deep water wave energy as it crosses the shelf nearshore and surfzone depending on the deep water wave characteristics and shelf and inshore morphology resultant breaker wave energy may be high moderate or low and the accompanying beach surfzone morphodynamic state in fine to medium sand beaches either dissipative intermediate or reflective dissipative beaches have wide surfzones with shore parallel bar s and channel s and predominantly shore normal circulation intermediate beaches are characterised by rip circulation crescentic transverse bars and megacusps and reflective beaches by a barless surfzone and steep cusped or bermed beach each beach form has a characteristic level of beach stability zone of sediment storage and mode of beach and dune erosion landward aeolian sediment transport of swash deposited sand section b is dependent on the subaerial beach topography and the aerodynamic flow regime across that topography characteristic profile shapes are ascribed to each beach type dissipative intermediate and reflective aeolian sand transport rates are potentially highest on dissipative beaches moderate on intermediate beaches and lowest on reflective beaches these rates determine the potential size of foredunes which are correspondingly largest on dissipative beaches and smallest on reflective beaches the combination of mode and frequency of beach dune erosion rates of aeolian sand transport and foredune volume and morphology provide an explanation of the nature and morphology of landward occurring large scale dune systems dissipative beaches are frequently characterised by large scale transgressive dune sheets intermediate by a trend from large scale parabolic dune systems high wave energy to small scale blowouts low wave energy and reflective beaches by minimal dune development

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

diffusional gradients at the crystal melt interface and their effect on the compositions of melt inclusions melt inclusions are widely believed to represent melts from which host crystals grew melt inclusions represent melt adjacent to growing crystals where compositional gradients exist due to preferential incorporation or exclusion of components by the crystallizing mineral the possibility arises therefore that melt in inclusions may differ significantly from melt which was more remote from growing crystals at the time the crystals grew we have tested this possibility by analyzing 45 major minor and trace components in 50 to 400 m diameter melt inclusions in phenocrysts from the rhyolitic bishop tuff california the following observations indicate that the effects of compositional gradients on chemical compositions of melt inclusions are negligible 1 melt inclusions in quartz and sanidine phenocrysts have indistinguishable compositions 2 no correlation is observed between sizes of melt inclusions and their chemical compositions 3 ten melt inclusions in four quartz phenocrysts from a single

data files from 3d velocity structure around the source area of the 1999 chi chi taiwan earthquake before and after the mainshock our study seeks to obtain a more detailed 3d velocity structure for the region surrounding the chi chi source volume both before and after the chi chi earthquake through tomographic inversion we have computed 3d v p and v p v s models using the high quality data set from local earthquakes as recorded by the taiwan central weather bureau seismographic network cwbsn we have selected 760 chi chi aftershocks with 12 568 p and 9 915 s wave arrival times that are used in this study in order to examine whether the large chi chi earthquake sequence has changed the crustal properties we have used another data set selected from the cwbsn database from 1993 to 1999 this includes arrival times of 22 500 p and 14 460 s wave arrival times from 975 events

zr nb ree mineralization in peralkaline granites from the amis complex brandberg namibia evidence for magmatic pre enrichment from melt inclusions the amis complex is a late intrusive phase associated with the brandberg anorogenic granite intrusion it consists of peralkaline arfvedsonite bearing granitic and pegmatitic dikes and sills and is characterized by locally extreme enrichments in ree and rare metals with high charge ionic radius ratios such as zr and nb the highest concentrations e g 1 7 wt zr 0 3 wt nb 0 5 wt total ree are found in aegirine albite aplites that formed around arfvedsonite pegmatite cores quartz hosted melt inclusions in coarse grained arfvedsonite granite and pegmatite give unequivocal evidence that the peralkaline composition and rare metal enrichments are primary magmatic features electron microprobe and sims analyses of rehomogenized inclusion glasses reveal their peralkaline high si rhyolite compositions avg molar na k al 1 1 and very high contents of h2o max 10 6 wt and f 2 2 wt inclusion glasses also have high concentrations of incompatible trace elements including nb min 803 ppm zr min 3 187 ppm and ree y min 1 271 ppm the ree zr and nb compositions of the aegirine albite aplites plot along the same linear enrichment trends as the melt inclusion glasses and y ho ratios mostly display unfractionated near chondritic values the chemical and textural features of the aegirine albite aplites are compatible with an origin by rapid crystallization compositional quenching after volatile loss from a residual peralkaline granitic melt of a composition like that of the melt inclusions interaction of postmagmatic fluorine rich aqueous fluids with the arfvedsonite granites caused local remobilization of ree and secondary mineralization of fluorocarbonate phases such as bastnaesite and fractionation of y and ho

tungsten solubility in evolved granitic melts an evaluation of magmatic wolframite abstract a variety of parameters that potentially control the solubilities of synthetic hubnerite mnwo4 and ferberite fewo4 in haplogranitic melts rich in fluxing compounds have been determined at 200 mpa in order to test the hypothesis that wolframite can occur as a magmatic mineral the melts considered representative of highly evolved pegmatites contain 1 1 1 7 and 2 02 wt of li2o p2o5 and b2o3 respectively although the molar al na k ratio is one if li is considered to be an alkali element the molar al na k li asili of the melt is 0 88 and the melt is peralkaline hubnerite and ferberite solubilities at 800 c are strongly controlled by melt composition they are much lower in subaluminous melt asili 1 05 than in peralkaline melt by contrast hubnerite and ferberite solubilities are nearly independent of the fluorine content of the melt for up to 8 wt f hubnerite and ferberite solubilities at 800 c are also nearly independent of oxygen fugacity over a log f o 2 range of approximately ni nio 3 to ni nio 2 which implies that the predominant oxidation state of tungsten in the melts is 6 even at moderately reduced conditions a series of experiments on haplogranitic melt rich in fluxing compounds with 0 and 6 wt f at 850 650 c shows that temperature strongly influences hubnerite solubility e g the solubility product of hubnerite k sp hub in the melts with 6 wt f decreases from 71 0 7 9 10 4 mol2 kg2 at 850 c to 4 4 2 3 10 4 mol2 kg2 at 650 c our experimental results show that ferberite solubilities are much higher than those of hubnerite with the same composition of melt but the mn fe and w concentrations in natural melt inclusions indicate that these melts were undersaturated with wolframite at 800 c however flux rich melts crystallize at lower temperatures in nature and the occurrence of natural magmatic wolframite was evaluated by comparing experimental solubility product values extrapolated to 500 c with wolframite activities at these temperatures magmatic wolframite is unlikely in flux rich peralkaline melts but by contrast flux rich subaluminous to peraluminous melt inclusions appear to have been saturated with wolframite at approximately 500 c because of the strong temperature dependence of wolframite solubility the dominant effect of fluxing compounds is to lower the solidus temperature of the melt

the thorite mineralization in the madeira sn nb ta world class deposit pitinga brazil abstract the world class sn nb ta madeira deposit is located in the pitinga mine northern brazil the deposit is associated with the albite enriched granite facies of the a type madeira granite 1820 ma the mine commercially extracts tin cassiterite nb and ta u pb pyrochlore and columbite fluorine cryolite y ree xenotime zr zircon u u pb pyrochlore and zircon and th thorite are potential byproducts this work presents a detailed study of thorite mineralization in the albite enriched granite subfacies the albite enriched granite core the albite enriched granite border and associated pegmatites the madeira deposit is revealed in this work to be among the largest th deposits in the world with 164 mt of homogeneously dispersed ore average grade of 759 ppm tho2 in the rock and higher concentrations up to 1 8 wt tho2 in small pegmatites average of 0 51 wt tho2 thorite compositions are either close to the thorite pole or correspond to relatively limited substitutions in the thorite zircon xenotime coffinite solid solution system the concentration of fe in thorite ranges from 0 11 wt to 29 56 wt fe2o3 and in many cases is considered to be of structural nature as well as part of the content of f up to 6 02 wt f thorites of all subfacies were strongly affected by hydrothermal alteration related to f rich low temperature aqueous fluids the hydration of thorite allowed the introduction of m3 cations y ree fe and al and f and caused losses in si and th contents average of 48 wt tho2 the alteration also created a fe rich halo in thorite with associated secondary minerals likely th fe hydroxyfluorides and y th fe fluorcarbonates the th u average ratios in bulk rock are 1 85 in the albite enriched granite border 3 82 in the albite enriched granite core and 19 85 in the associated pegmatites this variation reflects a pattern of magmatic evolution with higher availability of u in earlier stages and u depletion in later stages in pitinga the th and u mineralization are divided into different minerals formed at distinct stages of magma evolution this feature is related to fluorine enrichment and high alkalinity of the magma that strongly inhibited the early crystallization of zircon as well as columbite and favored the early appearance of u pb pyrochlore when crystallization of hydrous silicates reduced alkalinity crystallization of zircon from a magma depleted in u nb ta and lree became intense accompanied by thorite and xenotime

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

tantalite mn from the borborema pegmatite province northeastern brazil conditions of formation and melt and fluid inclusion constraints on experimental studies carbon dioxide rich fluid and carbonate rich aluminosilicate melt inclusions in tantalite mn from the alto do giz pegmatite in the borborema pegmatite province northeastern brazil were investigated to constrain the formation of the host crystals the results demonstrate that in the alto do giz pegmatite water and alkaline carbonate rich fluids and melts are responsible for the transport and deposition of tantalite mn at temperatures around 600 c and about 4 kbar moreover evidence is presented to show that during crystallization of the tantalite mn three different components coexisted which are now trapped as separate inclusions two immiscible silicate melts types a and b melt inclusions and a co2 rich aqueous fluid we hypothesize that immiscible fluid separation may have been a critical factor in producing the water and alkaline carbonate rich fluids and melts necessary for ta and nb transport since the tantalite mn crystallized during pegmatite formation this mechanism must also have implications for pegmatite genesis in general

erratum postglacial relative sea level change port au port area west newfoundland we first report pollen and foraminifera analyses and radiocarbon dates from two cores taken from salt marsh deposits bordering port au port bay southwestern newfoundland results show that relative sea level rsl stood at 2 8 m below present higher high water level hhwl at 2770 300 years bp and at 1 8 m at 2365 175 years bp at the core sites they permit calculation of a rate of late holocene rsl change from western newfoundland we then report other available dates bearing on the earlier rsl record of this area a date of 5800 200 years bp fixes the age of minimum rsl in port au port bay at 11 14 m below present a date of 9350 120 years bp from st george s provides a minimum age for the passage of sea level below present there a date of 12 600 140 years bp from stephenville fixes a sea level at 29 m above present whereas one of 13 600 110 years bp from abrahams cove dates the marine limit at 44 m these geographically restricted data closely constrain a curve of postglacial rsl change

formation of extremely f rich hydrous melt fractions and hydrothermal fluids during differentiation of highly evolved tin granite magmas a melt fluid inclusion study quartz crystals from topaz zinnwaldite albite granites from zinnwald erzgebirge germany contain in addition to primary and secondary fluid inclusions fis abundant crystalline silicate melt inclusions mis with diameters up to 200 m these mis represent various stages of evolution of a highly evolved melt system that finally gave rise to granite related sn w mineralization the combination of special experimental techniques with confocal laser raman microprobe spectroscopy and empa permits precise measurement of elevated contents of h2o f and b in re homogenized mis the contents of h2o and f were observed to increase from 3 to 30 and 1 9 to 6 4 wt respectively during magma differentiation however there is a second mi group very rich in h2o with values up to 55 wt h2o and an f concentration of approximately 3 wt ongoing enrichment of volatiles h2o f b and cl and of cs and rb can be explained in terms of magma differentiation triggered by fractional crystallization and thus is suggested to reflect elemental abundances in natural magmas and not boundary layer melts partitioning between melt and cogenetic fluids has further modified the magmatic concentrations of some elements particularly sn the coexistence of two types of mis with primary fis indicates fluid saturation early in the history of magma crystallization connected with a continuous sequestration of sn f and b the results of this study provide additional evidence for the extraordinary importance of the interplay of h2o f and b in the enrichment of sn during magma differentiation by decreasing the viscosity of and increasing the diffusivity in the melts as well as by the formation of various stable fluoride complexes in the melt and coexisting fluid

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

water in granite and pegmatite forming melts article i nfo in this paper we have compiled water concentration data obtained from melt inclusion in minerals mostly quartz and topaz from granites and pegmatites a small number of data come from analysis of natural glasses about 4600 melt inclusions are from granites and about 2100 melt inclusions are from pegmatites another 4159 values are from melt inclusions and glasses of rocks with more than 66 g g sio2 are added belonging to a recent compilation the total of 10 859 melt inclusions provides a statistically significant basis from which to derive some conclusions generally the water concentration in granite melt inclusion is b10 g g with three maxima at 4 0 1 3 5 9 1 2 and 8 1 1 1 g g water for pegmatites a larger range of water contents was found from 2 to more than 50 g g water with two distinct maxima at 10 5 8 1 and 26 2 14 3 g g we show that the great spread and the generally high water content of the pegmatite forming melts as sampled by melt inclusions are the result of melt melt immiscibility pro cesses connected with the formation of conjugate melt fraction with contrasting physical and chemical char acteristics which have also a major influence on the element partitioning between such fractions in this paper we also discuss viscosity as an important transport property of natural silicate melts and we show that due to high primary water concentration in the pegmatite forming melts their viscosity is very low over a wide range of temperatures in the case of water rich peralkaline melt fractions the viscosity can decrease still further together these suggest that liquidus undercooling as the major cause of pegmatite textures is redundant furthermore we demonstrate that the effect of boron carbonates and bicarbonates on pegmatite melts these two last mostly ignored in the past have a large influence on the melt structure and they enable pegmatite formation in the absence of the usual discussed fluxing elements such as f and p

nearly contemporaneous evolution of the a and s type fractionated granites in the krusne hory erzgebirge mts central europe abstract the krusne hory erzgebirge mountains is one of the best known provinces of granite magmatism and associated metallogenesis in europe variscan magmatic activity in the krusne hory erzgebirge area spanned the period from 330 to 295 ma for much of this time two types of magma were generated and emplaced in close proximity in this province strongly peraluminous p rich s type melts were formed alongside slightly peraluminous p poor melts a type two suites of strongly peraluminous p f li rb cs u sn rich and zr th y hree poor magmas were intruded in rapid succession over a period of about 10 ma about 330 320 ma over the entire region of the krusne hory several peraluminous rhyolitic dykes near gottesberg mark an isolated event at about 295 ma slightly peraluminous f li rb cs sn zr y hree rich and p poor magmas were intruded in several events separated in space and time 325 295 ma both magmatic episodes culminated with strongly fractionated subvolcanic granite intrusions accompanied by explosive brecciation and followed by sn w mineralization of greisen type successive volcanic eruption of rhyolites and dacites of s type and rhyolites of a type form the fill of the altenberg teplice caldera atc thus demonstrating the close temporal and spatial relationship between these two types of magma when these two geochemically distinct types of rock are in direct contact then the rocks of a type are always younger the absolute time difference between the two types can range from less than 1 ma the first eruption of the teplice rhyolite versus the schonfeld dacite in the atc to about 15 ma eruption of rhyolites at gottesberg versus emplacement of the eibenstock granite the assumed protolith of all late variscan granites in the area of krusne hory erzgebirge is a mixture of fertile quartzo feldspathic rocks with micaceous metapelites enriched in lile and sn w the differences in chemical composition of s and a type melts originated from local changes in the proportion of quartzo feldspathic and pelitic lithologies different pt conditions of melting the degree of melting and the degree of metamorphic dehydratation of the protolith prior to the melting

segregation of magmatic fluids and their potential in the mobilization of platinum group elements in the south kawishiwi intrusion duluth complex minnesota evidence from petrography apatite geochemistry and coexisting fluid and melt inclusions abstract pegmatitic and other felsic rock pockets and dike like intrusions are abundant in the south kawishiwi intrusion of the duluth complex including the basal cu ni pge mineralized units these occurrences are found as pockets pods or as veins and contain abundant accessory apatite and quartz quartz hosts primary fluid inclusions as well as silicate melt inclusions combined microthermometry and raman spectroscopy helped to determine the bulk composition of primary fluid inclusions that are co 2 rich 95 mol and contain small amounts of h 2 o 4 5 mol ch 4 0 4 mol and trace n 2 respectively this combined technique also made it possible to measure total homogenization temperatures of the inclusions th tot 225 10 c otherwise not detectable during microthermometry silicate melt inclusions have been quenched to produce homogeneous glasses corresponding to the original melt composition of the entrapped melt is granitoid peraluminous and is very poor in mafic components we interpret the melt as a product of partial melting of the footwall rocks due to the contact effect of the south kawishiwi intrusion the presence of co 2 in the vapor bubbles of the quenched melt inclusions and petrographic evidence suggest that the fluid and melt inclusion assemblages are coeval the composition of the fluid and melt phase implies that the fluid originates from the mafic magma of the south kawishiwi intrusion and the fluid and melt phases coexisted as a heterogeneous melt fluid system until entrapment of the inclusions coexistence of primary fluid and melt inclusions makes it possible to calculate a minimum entrapment pressure 1 7 kbar and thus estimate formation depth 5 8 km for the inclusions chlorine is suggested to behave compatibly in the silicate melt phase in the fluid melt system represented by the inclusions indicated by the high up to 0 3 cl concentrations of the silicate melt and co 2 rich nature of the fluid apatite halogen contents provide further details on the behavior of cl apatite in pegmatitic pockets often has elevated cl concentrations compared to troctolitic rocks suggesting enrichment of cl with progressive crystallization systematic trends of cl loss at some differentiated melt pockets suggest that in some places cl exsolved into a fluid phase and migrated away from its source the segregation of cl from the melt is probably inhibited by the presence of co 2 rich fluids until the last stages of crystallization increasing the potential for the development of late stage saline brines platinum group minerals are often present in microcracks in silicate minerals in late stage differentiated sulfide veinlets and in association with chlorapatite indicating the potential role of cl bearing fluids in the final distribution of pges

the miarolitic pegmatites from the konigshain a contribution to understanding the genesis of pegmatites in this paper we show that the crystallization of miarolitic pegmatites at konigshain started at about 700 c in melts containing up to 30 mass water such high water concentration at low pressures 1 3 kbar is only possible if the melts are peralkaline such peralkaline melts are highly corrosive and reacted with the wall rock here the granite host forming the graphic granite zone in part via a magmatic metasomatic reaction with cooling the water concentration in some melt fractions increased up to 50 mass h2o the melt dominated system ends below 600 c and passes into a fluid dominated system the beginning of which is characterized by strong pressure fluctuations caused by the change of oh and co32 in the melt to molecular water and co2 we note two generations of smoky quartz one crystallized above the transition of quartz 573 c and one below both of which contain melt inclusions this indicates that some melt fraction remains during at least the higher temperature portion of the growth of minerals into the miarolitic cavity contradicting the view that minerals growing into a pegmatite chamber only do so from aqueous fluids we show that the konigshain miarolitic pegmatites are part of the broad spectrum of pegmatite types and the processes active at konigshain are representative of processes found in most granitic pegmatites and are thus instructive in the understanding of pegmatite formation in general and constraining the composition and characteristics of pegmatite forming melts

be daughter minerals in fluid and melt inclusions implications for the enrichment of be in granite pegmatite systems the study of re homogenized melt inclusions in the same growth planes of quartz of pegmatites genetically linked to the variscan granite of the ehrenfriedersdorf complex erzgebirge germany by ion microprobe analyses has determined high concentrations of be up to 10 000 ppm in one type of melt inclusion as well as moderate concentrations in the 100 ppm range in a second type of melt inclusion generally the high be concentrations are associated with the h2o and other volatile rich type b melt inclusions and the lower be concentration levels are connected to h2o poor type a melt inclusions both inclusion types representing conjugate melt pairs are formed by a liquid liquid immiscibility separation process this extremely strong and very systematic scattering in be provides insights into the origin of be concentration and transport mechanisms in pegmatite forming melts in this contribution we present more than 250 new analytical data and show with ion microprobe and fs la icpms studies on quenched glasses as well as with confocal raman spectroscopy of daughter minerals in unheated melt inclusions that the concentrations of be may achieve such extreme levels during melt melt immiscibility of h2o b f p li enriched pegmatite forming magmas starting from host granite with about 10 ppm be melt inclusions with 10 000 ppm be correspond to enrichment by a factor of over 1 000 this strong enrichment of be is the result of processes of fractional crystallization and further enrichment in melt patches of pegmatite bodies due to melt melt immiscibility at fluid saturation we also draw additional conclusions regarding the speciation of be in pegmatite forming melt systems from investigation of the be bearing daughter mineral phases in the most h2o rich melt inclusions in the case of evolved volatile and h2o rich pegmatite systems b p and carbonates are important for the enrichment and formation of stable be complexes

foredunes and blowouts initiation geomorphology and dynamics this paper reviews the initiation dynamics geomorphology and evolution of incipient foredunes established foredunes and blowouts incipient foredunes may be initiated in a variety of ways leading to the formation of ramps terraces or ridges depending on progradation rates vegetation type and cover sediment transport rates and scale of erosional processes vegetation cover morphology growth rates and types combine with aerodynamic processes to determine dune and swale morphology established foredunes are classified into five morpho ecological types and the flow behaviour over two types is detailed a new model of foredune evolutionary paths at various possible time scales is presented blowout initiation dynamics and sediment transport and evolution is examined throughout the review the gaps in present understanding of dune processes and a range of ideas for new research possibilities are provided

melt inclusions in quartz from an evolved peraluminous pegmatite geochemical evidence for strong tin enrichment in fluorine rich and phosphorus rich residual liquids abstract we have investigated the magmatic evolution of a late stage f and p rich pegmatite forming aluminosilicate liquid and the geochemical controls on magmatic mineralizing processes by remelting totally crystallized melt inclusions in quartz and analyzing the quenched glass by epma and sims the quartz phenocrysts were sampled from a pegmatite that occurs in a variscan granite genetically associated with cassiterite and wolframite mineralized greisen veins at the ehrenfriedersdorf sn w deposit central erzgebirge se germany the melt inclusion compositions imply that the pegmatite forming liquid achieved extreme levels of chemical differentiation it contained high abundances of sn f p li rb cs nb ta and be and abnormally low concentrations of ca y sr and ree for a granite and it was strongly peraluminous the molar al 2 o 3 cao na 2 o k 2 o ranged from 1 3 to 2 0 fractions of the pegmatite forming liquid were extremely enriched in p 2 o 5 f al 2 o 3 and the molar abundances of f p in the glasses correlate strongly with moles of network modifying al ions implying that the bulk liquid included f p and al bearing complexes formation of these complexes reduced the activities of f p and al in bulk liquid suppressed the crystallization of magmatic topaz and p rich minerals and allowed the liquid to become enriched in these constituents some fractions of the ehrenfriedersdorf aluminosilicate liquid contained 1000 2000 ppm sn these levels of sn enrichment were up to 2 orders of magnitude greater than that ever reported for nonmineralized metaluminous and peraluminous igneous materials and are consistent with some experimentally derived sn solubilities in cassiterite saturated granitic liquids at geologically relevant pressures and temperatures this concordance implies that cassiterite could have crystallized directly from this highly evolved p and f rich peraluminous granitic liquid without the involvement of hydrothermal fluids

geology and genesis of the toongi rare metal zr hf nb ta y and ree deposit nsw australia and implications for rare metal mineralization in peralkaline igneous rocks the toongi deposit located in central nsw australia hosts significant resources of zr hf nb ta y and ree within a small ca 0 3 km2 rapidly cooled trachyte laccolith toongi is part of regional late triassic to jurassic alkaline magmatic field but is distinguished from the other igneous bodies by its peralkaline composition and economically significant rare metal content that is homogenously distributed throughout the trachyte body the primary ore minerals are evenly dispersed throughout the rock and include lueshite natroniobite and complex na fe zr nb y ree silicate minerals dominated by a eudialyte group mineral egm the egm occurs in a unique textural setting in the rock commonly forming spheroidal or irregular shaped globules herein called snowballs within the rock matrix the snowballs are often protruded by aegirine and feldspar phenocrysts and contain swarms of fine aegirine and feldspar grains that often form spiral or swirling patterns within the snowball secondary ore minerals include ree carbonates y milarite catapleiite and gaidonnayite that fill fractures and vesicles in the rock based on bulk rock geochemical and nd isotope data and thermodynamic modelling of magma fractionation the alkaline rocks of the region are interpreted to represent extrusive to hyperbyssal products of mantle derived magma that ponded at mid crustal levels ca 0 3 gpa and underwent extensive fractionation under low oxygen fugacity conditions the high na2o peralkaline nature of the toongi deposit trachyte developed via extensive fractionation of an alkali olivine basalt parental magma initially in the mid crust and subsequently at shallow levels ca 0 1 gpa this extended fractionation under low fo2 and relatively low h2o activity conditions limited volatile release and allowed build up of rare metal contents to ore grades we speculate that the ore minerals may have originally formed from rare metal rich sodic silicate melt that formed immiscible globules subsequently crystallized to egm in the magma shortly before emplacement and rapid cooling subsequent hydrothermal alteration caused relatively limited and localized remobilization of some ore metals into fractures and vesicles in the rock

vegetation dynamics on eroding to accreting beach foredune systems florida panhandle vegetation surveys were conducted on a variety of coastal foredunes in a largely natural region along the gulf county region of the florida panhandle species presence absence and percentage cover were surveyed on 12 foredune profiles during different seasons the vegetation data were analyzed using the shannon wiener diversity index and sorensen index uniola sp and andropgon sp were the dominant species on foredunes uniola sp was found predominantly on the gulfward facing or stoss slopes and andropgon sp was found to be dominant on the inland or lee slopes of foredunes while they are present on all foredunes their presence and percentage cover are dominant on rapidly prograding coasts prograding accretional beaches had higher sorensen index values i e higher similarities than did the foredune vegetation profiles on eroding beaches diversity as indicated by the shannon wiener analysis h is greatest on the highest and generally eroding dunes foredune diversity increased with foredune height and the tallest foredunes were found on shorelines with relatively low erosion rates where dunes were slowly translating landwards cannibalizing older dunes and moving into areas colonized by late successional species such as quercus sp these observations of foredune species richness diversity profile similarities and the use of ecological indices can provide excellent proxy evidence of shoreline dynamics and in particular the degree of beach erosion and accretion in the absence of historical erosion accretion data copyright 2013 john wiley sons ltd

dating multiply overprinted sn mineralized granites examples from the erzgebirge germany granites and primary tin mineralization in the erzgebirge were dated using 1 conventional u pb dating of uraninite inclusions in mica 2 rb sr dating of inclusions in quartz that represent highly evolved melts 3 re os dating of magmatic hydrothermal molybdenite and 4 chemical th u pb dating of uraninite conventional isotope dilution and thermal ion mass spectrometry and chemical th u pb dating of uraninite in granites from the ehrenfriedersdorf mining district provide ages of 323 9 3 5 ma 2 greifenstein granite and 320 6 1 9 and 319 7 3 4 ma 2 both sauberg mine in agreement with u pb apatite ages of 323 9 2 9 and 317 3 1 6 ms 2 both sauberg mine rb sr analysis of melt inclusions from zinnwald gives highly radiogenic sr isotopic compositions that with an assumed initial sr isotopic composition permit calculation of precise ages from single inclusions the scatter of the data indicates that some quartz hosted melt inclusions have been affected by partial loss of fluid exsolved from the melt inclusion re os dating of two molybdenite samples from altenberg provides ages of 323 9 2 5 and 317 9 2 4 ma 2 together with age data from the literature our new ages demonstrate that primary tin mineralization and the emplacement of the large sn specialized granites in the erzgebirge fall in a narrow range between 318 and 323 ma primary sn mineralization occurred within a short interval during post collisional collapse of the variscan orogen and was essentially synchronous over the entire erzgebirge in contrast to earlier claims no systematic age difference between granites of the eastern and western erzgebirge was established furthermore our data do not support a large age range for late variscan granites of the erzgebirge 330 290 ma as has been previously suggested

comment on a petrologic assessment of internal zonation in granitic pegmatites by david london 2014 london 2014 provides an interesting article which presents a study of pegmatite zonation which is of considerable interest to students of pegmatites however although there is much to recommend it we take exception to his attempts to dismiss an extensive body of work on the use of melt inclusions to address the critical question of actual melt compositions during the evolution of pegmatites

crystallization conditions and evolution of magmatic fluids in the harney peak granite and associated pegmatites black hills south dakota evidence from fluid inclusions abstract a microthermometric study of inclusions in granites and pegmatites in the proterozoic harney peak granite system identified four types of inclusions type 1 inclusions are mixtures of co2 and h2o and have low salinities on average 3 5 wt nacleq type 2 inclusions are aqueous solutions of variable salinities from 0 to 40 wt nacleq type 3 inclusions are carbonic dominated by co2 with no detectable water and type 4 inclusions consist of 20 to 100 solids with the remaining volume occupied by a co2 h2o fluid many inclusions have a secondary character however a primary character can be unambiguously established in several occurrences of the type 1 inclusions these inclusions were trapped above the solidus and represent the exsolved magmatic fluid the secondary populations of types 1 2 and 3 probably formed as a result of reequilibration and unmixing of the type 1 fluid that progressively changed composition and density with decreasing temperature and pressure and was finally trapped along healed microfractures under subsolidus conditions type 4 inclusions are primary and are interpreted to be trapped fluid bearing complex silicate melts that subsequently solidified or underwent other posttrapping changes it is demonstrated that primary type 1 fluid inclusions that coexist with crystallized melt inclusions in the complex li bearing tin mountain pegmatite were trapped along the two fluid phase boundary in the system co2 h2o nacleq consequently the temperature and pressure conditions of trapping are identical to the bulk homogenization conditions on average 340 c and 2 7 kbar these conditions indicate that this li cs rb p and b rich pegmatite crystallized at some of the lowest known temperatures for a silicate melt in the crust an internally consistent empirical solvus surface in p t xco2 coordinates was generated for the pseudobinary co2 h2o 4 3 wt nacleq pegmatite fluid system distribution coefficients for the major species co2 h2o nacl and ch4 between the immiscible co2 rich and h2o rich fluid phases as a function of pressure and temperature were extracted from data for the two cogenetic fluid inclusions types

li nb ta mineralization in the jurassic yifeng granite aplite intrusion within the neoproterozoic jiuling batholith south china a fluid rich and quenching ore forming process abstract the neoproterozoic jiuling batholith in northwestern jiangxi province south china is one of the largest batholiths in the nanling range and it is intruded by mesozoic granitic intrusions associated with mineralization the jurassic yifeng granitic pluton intrudes to the southern part of the jiuling batholith and comprises li rich muscovite li mus granite trilithionite tri granite and aplite dikes the granitic rocks are enriched in rare metals li rb cs nb ta we conducted whole rock geochemical analyses undertook columbite u pb dating and examined the textures and chemistry of feldspars micas and the accessory minerals montebrasite columbite group minerals cgms microlite cassiterite and zircon all three granitic rock types have high li contents up to 6200 ppm and the 7li values of the li mus granite and aplite are 3 55 0 14 and 5 34 0 04 respectively the isolated grains of cgms and cassiterite in the aplite are magmatic products but intense fluid activity in the later stages and quenching resulted in unique mineral aggregates of cassiterite cgms zircon the nb ta mineralization of the li mus granite took place at 144 5 ma according to columbite u pb dating and this age is similar to that of the neighbouring yichun granitic pluton to the south moreover both the yifeng and yichun plutons contain p rich rare metal bearing li f granitic rocks that contain p rich feldspars montebrasites amblygonites cs rich lepidolites cgms close to the mn endmember and hf rich zircons it is inferred that a metallogenic district characterized by li nb ta mineralization exists in northwestern jiangxi province thus providing a reliable guide for further exploration

origin of miarolitic pegmatites in the konigshain granite lusatia abstract in this study we examine an interesting occurrence of miarolitic pegmatites in the konigshain granite of the lusatia region of the bohemian massif this granite is characterized by the extensive development of micro sized miarolitic pegmatites typically with diameters of 5 to 15 mm irregularly distributed through its upper levels and larger miarolitic pegmatites up to 1 m in the uppermost levels this granite also shows evidence of varied forms of transport of extremely volatile rich residual melts fluids in the form of more or less discrete inter granular melt bodies and associated magmatic quartz veins formed in tectonic fissures together these provide evidence for the origin of miarolitic pegmatites both in the specific case of konigshain and more generally our evidence suggests that miarolitic pegmatites form from volatile and alkali rich residual melts ranging from 10 to 50 h 2 o far more than typical granitic melts but far more silicate components than aqueous fluids or vapor suggested by some authors using melt inclusions in quartz from the aplitic and graphic granite zones in miarolitic pegmatites in the konigshain granite we show that two different inclusion populations are present we provide evidence that the first inclusion population are those related to the primary granite at the level of intrusion and the second were trapped during the re crystallization of the granite wall rocks by silicate rich supercritical fluids moving through the solid crystal framework with a porosity 0 see clarke et al 2013 our results show that a significant volume fraction of the miarolitic pegmatites was not created by a pegmatite forming fluid but formed in situ by re crystallization of wall rocks triggered by highly reactive volatiles exsolved from the pegmatite forming melts evidence is also presented which suggests the nature and speed of emplacement of the konigshain granite this evidence may explain the unusual form and abundance of miarolitic pegmatites in the studied area and may have application to similar occurrences thus there is a mixture of features which are applicable to miarolitic pegmatites in general and others which help separate the overriding processes from the variations produced by local or regional chemical or tectonic characteristics

the combined effects of water and fluorine on the viscosity of silicic magmas abstract the newtonian viscosity of water plus fluorine bearing silicate melt of haplogranitic composition hpg8 has been determined viscosities of hpg8 melt with addition of 3 11 and 4 25 wt of f and up to 3 wt h2o have been obtained using a micropenetration technique in the interval 109 74 to 1011 84 pa s and temperatures varying from 370 to 700 c at ambient pressure determination of the temperature dependence of viscosity from this and previous studies permits the parameterization of the viscosity of melts containing water and fluorine having similar composition within a 0 3 log units standard error the viscosity of water bearing f rich haplogranitic samples is represented by a modified vogel fulcher tammann vft equation which provides a non arrhenian description of the temperature dependence of the viscosity the results of this study indicate that taken individually or together both h2o and f have a strong and similar effect on the viscosity of sio2 rich compositions this similarity between f2o 1 and h2o greatly simplifies the task of predicting viscosity for volatile rich highly silicic magmas the low viscosities of hydrous fluorine bearing granitic melts favour efficient crystallization fractionaction paths for these liquids controlling degassing paths and consequently the eruptive behaviour numerical simulations of eruptive events normally do not take into account the contribution of fluorine this may introduce a significant error in the description of the fluid dynamic properties of magma and therefore in the accurate prediction of eruptive scenarios as well as in hazard assessment studies fluorine unlike water remains dissolved in the melt at high concentrations and low confining pressures the incorporation of fluorine data and the modelling of fluorine bearing viscosity data are therefore of fundamental importance for simulations of magma dynamics and prediction of eruptive scenarios

ages and genesis of w sn and ta nb sn w mineralization associated with the limu granite complex guangxi china abstract the limu granite complex spans three granitic stages forming the largest indosinian ta nb sn w ore field in south china there includes quartz vein w sn type 1 mineralization associated with second stage granite as well as ta nb sn w mineralization associated with third stage granite including quartz feldspar vein type 2 pegmatite dike type 3 and disseminated type 4 mineralization to elucidate the magmatic evolution and genesis of these types of mineralization we obtained muscovite 40ar 39ar ages zircon la icp ms u pb ages and lu hf and nd isotopic trace element and geochemical compositions of the limu granite complex the limu granites are peraluminous a cnk 1 1 with negative nd t values 8 5 to 9 7 and tdm2 ages of 1780 1685 ma suggesting that they were derived mainly from partial melting of paleoproterozoic basement remnants of caledonian zircons 429 4 5 6 ma indicate caledonian granite melting in the source low zr hf pb ages of ca 203 ma and 40ar 39ar ages of ca 208 ma respectively we conclude that type 1 mineralization was formed at ca 214 ma and was hydrothermal in origin whereas ta nb sn w mineralization was formed at ca 208 203 ma and was of magmatic hydrothermal origin mantle derived heat from a long lived magma chamber was essential for the high temperature anatexis that formed ta nb sn w rich melts with the combined effects of crustal thickening during the indosinian orogeny local delamination asthenospheric upwelling and deep faulting facilitating the continuous supply of heat

annual to decadal morphodynamics of the foredune system at greenwich dunes prince edward island canada the purpose of this study was to quantify relationships between season sediment availability sediment transport pathways and beach foredune morphology at greenwich dunes pei this was done for periods ranging from a few days to multiple decades using erosion pins bedframe measurements annual surveys and digital photogrammetry using historical aerial photographs the relative significance of seasonal annual processes versus response of the foredune system to broader geomorphic controls e g relative sea level rise storms etc was also assessed the data show that there are clear seasonal differences in the patterns of sand supply from the beach to the foredune at greenwich and that there are differences in sediment supply to the foredune between the east and west reaches of the study area resulting in ongoing differences in foredune morphology they also demonstrate that models that incorporate wind climate alone or even models that include other factors like beach moisture would not be able to predict the amount of sediment movement from the beach to the foredune in this environment unless there were some way to parameterize system morphology especially the presence or absence of a dune ramp finally the data suggest that the foredune can migrate landward while maintaining its form via transfers of sediment from the stoss slope over the crest and onto the lee slope although the rate of foredune development or recovery after disturbance changes over time due to morphological feedback the overall decadal evolution of the foredune system at greenwich is consistent with and supports the davidson arnott 2005 conceptual model of dune transgression under rising sea level copyright 2012 john wiley sons ltd

a comparison of observed and theoretical postglacial relative sea level in atlantic canada two extreme models of late wisconsinan ice cover in atlantic canada and the northeastern u s a are shown to produce postglacial relative sea level curves that bracket existing field observations at six sites throughout the region this suggests that the true late wisconsinan ice distribution is probably intermediate to the two contrasting reconstructions proposed both ice models predict the existence of four relative sea level zones an innermost zone closest to the centre of glaciation in which relative sea level falls continuously throughout postglacial time an outermost zone in which it rises continuously and two transitional zones in which it first falls and then rises in varying proportions according to the distance from the ice margin the distinctive forms of the relative sea level curves are probably representative of each of the zones and are unlikely to be significantly perturbed even by large local ice readvances they therefore establish patterns with which future field data are expected to conform the form that the geological record of relative sea level change is likely to take within each zone is discussed and promising settings for the collection of new data are proposed the common practice of separating relative sea level into an isostatic and a eustatic component is analysed and shown to be incorrect as usually applied the practice is also shown to be unnecessary because the models discussed in this paper predict changes in relative sea level that can be compared directly with the observations

tantalum and niobium mineralization from f and cl rich fluid in the lepidolite rich pegmatite from the renli deposit in northern hunan china constraints of fluid inclusions and lepidolite crystallization experiments abstract lepidolite type pegmatite usually produces tantalum niobium ta nb resources however the role of the hydrothermal fluid in the ta nb mineralization remains controversial the pegmatite dike no 5 is a lepidolite rich dike in the ta nb pegmatite deposit in renli hunan china with a high grade ta2o5 in the lepidolite quartz core the fluid inclusions with primary features in the quartz from the core have a relatively high ths 270 290 c and salinity 10 wt nacleq the mineral features such as occurrences of pezzottaite and fluornatromicrolite as well as the assemblage of lepidolite quartz and albite further confirm that the fluid inclusions were entrapped in a na li cs f and cl rich fluid from which quartz and lepidolite crystallized these fluid inclusions were inferred to be trapped between 640 c and 530 mpa and 550 c and 350 mpa based on the fluid inclusion isochores and the lepdilite crystallization temperature pressure t p conditions that were determined via lepidolite crystallization experiments in aqueous solutions with a high fhf and a salinity of 10 wt nacl in a hydrothermal diamond anvil cell although the p t conditions are in accordance with the stability field of spodumene no spodumene was observed in the no 5 dike because of the high fhf in the fluid such li cs f cl rich fluids could be an indicator of the final layer liquid in the model of constitutional zone refining or b type fluid melt in the immiscibility model moreover it could dissolve the previous magmatic nb ta minerals in the form of li na cs ta nb o f cl 4 with ta nb remaining in the aqueous solution until the deposition of ta nb minerals during the crystallization of lepidolite and albite in lepidolite qaurtz core in no 5 dike in the renli deposit

three dimensional velocity structure in northern california coast ranges from inversion of local earthquake arrival times abstract the three dimensional p wave velocity structure in the upper crust in the northern california coast ranges from santa rosa to ukiah is obtained by simultaneous inversion of local earthquake and refraction travel time data for velocity and hypocentral parameters in this region where there are lateral heterogeneities the three dimensional inversion provides important results not found in two dimensional refraction studies the medium is parameterized with velocities at the intersections gridpoints of a nonuniform three dimensional grid travel times are calculated with approximate ray tracing along arcuate paths which are reasonable for lateral distances less than 45 km inversions with 5 to 10 and 2 to 3 km gridspacing achieved 80 per cent decreases in data variance the inversion with 2 to 3 km gridspacing reduced the rms residual level to approximately the level of timing error anomalously low velocities to at least 6 km depth are found along the maacama and healdsburg rodgers creek hrc fault zones the low velocity region is widest at the en echelon junction of the maacama and hrc fault zones low velocities are associated with the clear lake basin where there is a thick sequence of volcanics interbedded with sedimentary deposits there is a high velocity body located southeast of the geysers between the maacama and collayomi fault zones which may be associated with igneous intrusives or high grade metamorphism related to an underlying inferred partial melt body modeled in previous teleseismic travel time studies there is some indication in the vapor dominated geothermal reservoir of lower velocities relative to surrounding water saturated rock as has been shown in some laboratory experiments hypocenter locations obtained in the inversion show little variation from hypocenters obtained through inversion for one dimensional velocity model and station corrections for the inversion with 2 to 3 km gridspacing however some groups of events become more tightly clustered

laser raman spectroscopic measurements of water in unexposed glass inclusions a method is proposed for determining the water concentration in silicate melt inclusions mi by confocal micro raman spectroscopy without exposing the inclusions for measurement a prerequisite of all previous methods the latter is important for extremely water rich mi e g those in evolved granites and pegmatites which would loose h2o on exposure furthermore this technique permits determination of the water concentration in a single mi we use a comparative technique determining the total water content of a sample against a reference glass of known water content because this process is non destructive it does not preclude the subsequent use of other analytical techniques

foredune development on iles de la madeleine quebec atlantic canada the foredune in this cool temperate sediment abundant relatively high wind and wave energy environment is generally a single ridge with a mean height of 5 1 m max 11 4 m and width of 25 35 m pioneer vegetation is dominated by ammophila breviligulata four foredune types were identified scarped scarped with blowouts scarped with incipient foredune and nonscarped the first being the most common occupying more than 50 of the shoreline foredune erosion and retreat is occurring at an average rate of 0 8 m a 1 the marked differences in dune character between the west and east coasts of the islands are related to differences in wave energy and shoreline dissipativeness the higher energy west coast exhibits more dynamic dunes with more frequent blowouts which may develop into parabolic forms

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

near surface versus fault zone damage following the 1999 chi chi earthquake observation and simulation of repeating earthquakes we observe crustal damage and its subsequent recovery caused by the 1999 m7 6 chi chi earthquake in central taiwan analysis of repeating earthquakes in hualien region 70 km east of the chi chi earthquake shows a remarkable change in wave propagation beginning in the year 2000 revealing damage within the fault zone and distributed across the near surface we use moving window cross correlation to identify a dramatic decrease in the waveform similarity and delays in the s wave coda the maximum delay is up to 59 ms corresponding to a 7 6 velocity decrease averaged over the wave propagation path the waveform changes on either side of the fault are distinct they occur in different parts of the waveforms affect different frequencies and the size of the velocity reductions is different using a finite difference method we simulate the effect of postseismic changes in the wavefield by introducing s wave velocity anomaly in the fault zone and near the surface the models that best fit the observations point to pervasive damage in the near surface and deep along fault damage at the time of the chi chi earthquake the footwall stations show the combined effect of near surface and the fault zone damage where the velocity reduction 2 7 is twofold to threefold greater than the fault zone damage observed in the hanging wall stations the physical models obtained here allow us to monitor the temporal evolution and recovering process of the chi chi fault zone damage

the mineralogy of ba and zr rich alkaline pegmatites from gordon butte crazy mountains montana usa comparisons between potassic and sodic agpaitic pegmatites at gordon butte crazy mountains montana agpaitic nepheline syenite pegmatites intrude potassic alkaline rocks principally malignites and nepheline microsyenites all pegmatite veins are composed predominantly of potassium feldspar nepheline prismatic aegirine barytolamprophyllite wadeite eudialyte loparite ce and altered rinkite vudyavrite embedded in spherulitic and fibrous aegirine well differentiated veins contain pockets filled with calcite fluorapatite mangan neptunite mn ti enriched prismatic aegirine calcium catapleiite and an unidentified ca ti silicate the potassium feldspar corresponds to ba rich sanidine with relatively low na contents the nepheline contains low levels of sio2 and elevated fe contents the compositions of nepheline cluster in the lower portion of the morozewicz buerger convergence field indicating low temperature crystallization and or chemical re equilibration of this mineral the association of sanidine with nearly stoichiometric nepheline is unusual for agpaitic rocks and probably reflects inhibition of al si ordering in the feldspar by ba at least four types of clinopyroxene can be distinguished on the basis of their morphology and composition all these types correspond to al and ca poor aegirine typically 0 6 and 2 6 wt al2o3 and cao respectively the overall evolutionary trend of clinopyroxene in the gordon butte rocks is from fe poor diopside to aegirine augite in the malignites and nepheline microsyenites and culminates with the pegmatitic aegirine this trend is characteristic for potassic alkaline complexes and results from preferential partitioning of fe2 into biotite during the magmatic crystallization barytolamprophyllite in the pegmatites is primary as opposed to deuteric only a few crystals contain a core composed of lamprophyllite the evolutionary history of the gordon butte pegmatites can be subdivided into primary agpaitic and deuteric stages the earliest paragenesis to crystallize included accessory zircon and thorite sr rich loparite also precipitated relatively early serving as a major repository for sr ree and nb during the agpaitic stage diverse titano and zircono silicates barytolamprophyllite eudialyte wadeite and rinkite among others consumed most of the ba sr ti zr and nb still remaining in the melt the final stage in the evolution of the pegmatites involved interaction of the earlier formed mineral assemblages with deuteric fluids in common with the rocky boy pegmatites sr ree na rich fluorapatite ba fe titanates and ree bearing carbonates ancylite calcio ancylite and bastnasite parisite series are chief products of the deuteric stage the alteration of the primary mineral assemblages by deuteric fluids also produced muscovite zeolite pseudomorphs after nepheline replacement of wadeite and eudialyte by catapleiite group minerals re deposition of ba in the form of hyalophane baotite and benitoite and cation leaching from rinkite eudialyte and loparite the mineralogy of the pegmatites from gordon butte other potassic complexes and sodic agpaitic occurrences is compared in detail

the transition from granite to banded aplite pegmatite sheet complexes an example from megiliggar rocks tregonning topaz granite cornwall abstract the genetic relationship between a granite pluton and adjacent complex of rare metal pegmatite aplite banded sheets megiliggar sheet complex msc has been studied at the border of the tregonning topaz granite at megiliggar rocks cornwall sw england similarities in whole rock chemical and mineralogical compositions together with a gradual change in textures away from the granite margin provide strong evidence for a genetic link between the tregonning granite and msc the sheets are likely to represent apophyses of residual melt which escaped from the largely crystallized roof of the granite pluton the escaping melt was peraluminous had a composition near the f b li slightly enriched granite minimum and in comparison with other cornish granites was enriched in f li rb cs sn w nb ta and u and depleted in fe mg ca sr th zr and ree with increasing distance from the tregonning granite the silicate melt crystallized as homogeneous leucogranite sheets and banded complex sheets i e combinations of bands with granitic aplitic and pegmatitic textures then layered aplite pegmatites this sequence becoming progressively more depleted in the fluxing and volatile elements f li rb and cs but showing no change in zr hf ratios the fixed zr hf ratio is interpreted as indicating a direct genetic link parental melt between all rock types however the melt progressively lost fluxing and volatile elements with distance from the granite pluton probably due to wall rock reaction or fluid exsolution and migration via fractures differentiation of the primary melt into na li f rich and separate k b rich domains was the dominant chemical process responsible for the textural and mineral diversity of the msc on a large cliff section scale the proximal na li f rich leucogranite passes through complex sheets into k b rich aplite pegmatites whilst at a smaller

crustal melts below 400 c we propose that the internally zoned li bearing tin mountain pegmatite in the harney peak granite pegmatite system of the black hills south dakota crystallized from fluid rich compositionally complex melts at 400 350 c the low crystallization temperatures resulted from the combined fluxing effects of li b p h 2 o and carbonate anions the presence of hydrous silicate melts at temperatures of 350 c is revealed by microthermometric data on primary fluid inclusions cogenetic with crystallized melt inclusions mineral assemblages of the crystallized melt inclusions and chemistry of bulk fluid leachates indicate that the melts and fluids contained significant amounts of li and na as carbonates and or borates that acted as powerful fluxes the low temperatures give a new perspective on the stability of silicate melts in the crust

extreme chemical heterogeneity of granite derived hydrothermal fluids an example from inclusions in a single crystal of miarolitic quartz magma derived fluids are important in geologic processes e g metal sequestration and ore deposition but are intrinsically transient samples of magmatic fluids represented by fluid inclusions in a single zoned quartz crystal from a miarolitic cavity within a porphyritic leucogranite hosting the industrialnoe tin deposit northeastern russia were studied by using modern in situ analytical methods laser raman spectroscopy proton induced x ray emission the fluid inclusions are either dominated by vapor or by complex multiphase brines the inclusions within a given trapping plane have similar phase relationships however there are significant variations between inclusions in different healed fractures phase and chemical compositions of individual brine inclusions demonstrate significant compositional heterogeneity in terms of absolute element concentrations and ratios of high temperature magmatic fluids accumulated in the miarolitic cavity this finding suggests that fluids leaving a crystallizing magma may have variable initial compositions that are subsequently modified by reactions with the rocks while the fluid is in transit to a miarolitic cavity as well as by processes in the cavity such as mixing crystallization and boiling the inferred chemical diversity and fractionation of granite derived fluids at near magmatic conditions imply that fluids entering a cooler hydrothermal system are extremely complex and their metallogenic signature may differ from that of related ore deposits

earthquake locations and three dimensional crustal structure in the coyote lake area central california previous work on the simultaneous inversion method has been improved and extended to incorporate iterative solution for earthquake locations and laterally heterogeneous structure approximate ray tracing and parameter separation are important elements of the improved method application of the method to p wave arrival time data recorded by stations of the u s geological survey central california network yields a three dimensional model for the velocity structure of the upper crust in an area encompassing the rupture zone of the coyote lake earthquake of august 1979 very strong correlations between the velocity model and the geology and gravity and magnetic anomalies are observed improved estimates of the locations of earthquakes in the study area are also determined the relocation of explosions indicates epicentral accuracies of the order of a kilometer or better based on the revised hypocentral locations it is concluded that the san andreas fault is vertical in this area with no actual offset between the epicenters and the fault trace in contrast the calaveras has two or more active fault surfaces one nearly vertical and another dipping 75 to the northeast