use of surface controlled ree sectoral zoning in apatite from llallagua bolivia to determine a single crystal smnd age abstract surface structure controlled partitioning of rees between symmetrically nonequivalent crystal faces leads to sectoral zoning between the 0001 and 1010 sectors of vein filling apatites from llallagua bolivia absolute differences in the concentration of the analyzed rees between these sectors range from a factor of 9 5 in the case of la to a factor of 1 4 for yb the two sectors have different concentrations of sm and nd as well as significantly different sm nd ratios 147 sm 144 nd 0 3558 a sm nd isochron determined from petrographically constrained coeval portions of different sectors gives an age of 43 8 4 7 ma 95 confidence limits we believe that this calculated age represents the time of crystallization of the apatite the application of intracrystalline heterogeneities that formed due to differential partitioning at the crystal surface to dating of minerals is germane for any mineral in which sectoral or intrasectoral zoning is exhibited and may be used with other isotopic systems in which sufficient segregation of parent and daughter nuclides occurs and in which concentrations are sufficient for analysis of small intracrystalline samples

complex zoning in apatite from the idaho batholith a record of magma mixing and intracrystalline trace element diffusion apatite crystals in a sample of biotite granodiorite from the idaho batholith display complex chemical zoning characterized by abrupt changes in ree y si content more subtle variations in s na la yb and mn contents and petrographic evidence for multiple episodes of partial resorption the zoning is attributed to changes in melt composition resulting from magma mixing and differentiation although the possibility that some rounded cores may be inherited cannot be disproved high s contents in apatite cores and the presence of an included anhydrite grain indicate crystallization from an oxidized host magma divalent cations that occupy the apatite ca sites sr mn fe show evidence of having been redistributed between zones by intracrystalline diffusion whereas cations that participate in coupled substitutions involving the tetrahedral site si y ree na s were not readily redistributed the main ree substitution in this case is ree super 3 si super 4 ca super 2 p super 5 and ree diffusion is rate limited by slow si diffusion however exchange of lree e g lasm sub 1 on the ca sites does not involve si and proceeds more rapidly resulting in homogenization of la sm between zones within individual crystals relative diffusion rates inferred from zoning profiles in this study are mn sr fe and lasm sub 1 are faster than na s and layb sub 1 which are faster than si these data imply that ree patterns can be decoupled from ree abundances during diffusion and that even apatite zones or cores that appear sharply bounded in backscattered electron images may not retain their original chemical or sr nd isotopic traits

geophone orientation and coupling in three component sea floor data a case study we analyse the geophone orientation and coupling in a data set from the north sea based on the polarization of the water break on the sea floor we have derived processing algorithms for determining the receiver orientation for gimballed and non gimballed geophone systems for a gimballed system the problem reduces to a simple horizontal rotation however for a non gimballed system where all three geophone axes may vary due to varying acquisition conditions such as dipping sea floor twisting of recording cable etc the three orientation angles cannot be found directly from the recorded displacement vectors using the data redundancy within a common receiver gather a robust two stage method is derived for the non gimballed system in which all three orientations can initially be unknown testing on the north sea data set acquired with a gimballed system shows that the three component geophones in the data set are orientated satisfactorily within an error of 5 however there are some undesirable cross couplings between the vertical and horizontal geophones which results in leakage of shear wave energy from the horizontal components to the vertical components

geochemistry and origins of carbonate fluorapatite in seamount fe mn crusts from the pacific ocean abstract seamount phosphates are increasingly regarded as potential resources for rare earth elements ree and plus yttrium rey carbonate fluorapatite cfa formed within seamount ferromanganese fe mn crusts is the most common seamount phosphate mineral however reports on the mineralogy and geochemistry of cfa are few and thus its origin and acquisition of trace elements are not well understood in this study we analyzed the major and trace elements of cfa in fe mn crusts collected from western and central pacific seamounts to investigate the genesis of trace elements in the cfa this is the first study to use in situ analytical techniques such as electron microprobe analyzer epma and laser ablation inductively coupled plasma mass spectrometry la icp ms to analyze seamount cfa we found that the cfa hosts abundant minor and trace elements and propose that ionic substitutions are responsible for the high contents of so3 sio2 rey sr na fe and mn in the cfa veins found in the fe mn crusts i e sio32 and so42 substitute for po42 while ree3 y3 na fe2 and mn2 substitute for ca2 ree3 substitutions for ca2 in the cfa are charge compensated by na substitution for ca2 fourier transform infrared spectroscopy ftir analysis shows that co32 mainly substitutes for po42 in the cfa crystal structure and there is a minor substitution of po42 by co3f3 ocean water is the major source of the p and rey which when precipitated as seamount cfa is characterized by high ree 345 to 6016 ppm and heavy ree hree enrichments monazite grains dispersed in the seamount cfa contribute trace amount of rey these results shed light on the composition and element mobility of seamount cfa with economic potential which also provides valuable insights into global ocean chemical cycling e g ree

mineralogy geochemistry and the origin of high phosphorus oolitic iron ores of aswan egypt abstract the coniacian santonian high phosphorus oolitic iron ore at aswan area is one of the major iron ore deposits in egypt however there are no reports on its geochemistry which includes trace and rare earth elements evaluation texture mineralogy and origin of phosphorus that represents the main impurity in these ore deposits have not been discussed in previous studies in this investigation iron ores from three localities were subjected to petrographic mineralogical and geochemical analyses the aswan oolitic iron ores consist of uniform size ooids with snowball like texture and tangentially arranged laminae of hematite and chamosite the ores also possess detrital quartz apatite and fine grained ferruginous chamosite groundmass in addition to fe 2 o 3 the studied iron ores show relatively high contents of sio 2 and al 2 o 3 due to the abundance of quartz and chamosite p 2 o 5 ranges from 0 3 to 3 4 wt showing strong positive correlation with cao and suggesting the occurrence of p mainly as apatite x ray diffraction analysis confirmed the occurrence of this apatite as hydroxyapatite under the optical microscope and scanning electron microscope hydroxyapatite occurred as massive and structureless grains of undefined outlines and variable size 5 150 m inside the ooids and or in the ferruginous groundmass among trace elements v ba sr co zr y ni zn and cu occurred in relatively high concentrations 62 240 ppm in comparison to other trace elements most of these trace elements exhibit positive correlations with sio 2 al 2 o 3 and tio 2 suggesting their occurrence in the detrital fraction which includes the clay minerals ree ranges between 129 5 and 617 ppm with strong positive correlations with p 2 o 5 indicating the occurrence of ree in the apatite chondrite normalized ree patterns showed lree enrichment over hree la yb n 2 3 5 4 and negative eu anomalies eu eu 0 75 0 89 the oolitic texture of the studied ores forms as direct precipitation of iron rich minerals from sea water in open space near the sediment water interface by accretion of feo sio 2 and al 2 o 3 around suspended solid particles such as quartz and parts of broken ooliths the fairly uniform size of the ooids reflects sorting due to the current action the geochemistry of major and trace elements in the ores reflects their hydrogenous origin the oolitic iron ores of the timsha formation represent a transgressive phase of the tethys into southern egypt during the coniacian santonian between the non marine turonian abu agag and santonian campanian um barmil formations the abundance of detrital quartz positive correlations between trace elements and tio 2 and al 2 o 3 and the abundance mudstone intervals within the iron ores supports the detrital source of fe this prediction is due to the weathering of adjacent land masses from cambrian to late cretaceous the texture of the apatite and the ree patterns which occurs entirely in the apatite exhibits a pattern similar to those in the granite thus suggesting a detrital origin of the hydroxyapatite that was probably derived from the precambrian igneous rocks determining the mode of occurrence and grain size of hydroxyapatite assists in the maximum utilization of both physical and biological separation of apatite from the aswan iron ores and hence encourages the use of these ores as raw materials in the iron making industry

estimation of aqueous hcl and cl concentrations in felsic systems abstract two models are presented which can be used to make order of magnitude estimates of the concentration of hcl and cl in the magmatic volatile phase mvp one model is based primarily upon aplite chemistry and the other is based primarily on apatite chemistry the models are not entirely independent and additional information can be gained by using the models in conjunction with one another combining both methods allows for the calculation of a model bulk cl concentration of magmatic vapor both models are applied to a natural system the billy lake granite and rush creek quartz monzodiorite in the sierra nevada batholith of eastern california the bulk composition of aplite and other granitic rocks of vapor saturated near minimum melt compositions can be used to estimate maximum hcl total cl for the magmatic vapor phase the composition of the aplites in the billy lake rush creek blrc system has been used to determine model hcl kcl and hcl nacl for the vapor in equilibrium with the aplite melts both ratios are on the order of unity 1 1 these values suggest that the maximum hcl cl 1 3 corresponding to a concentration of hcl in the magmatic vapor of 0 02 molal if the magmatic system was saturated with a brine phase apatite compositions can be used to estimate the hcl concentration in the magmatic vapor as a function of temperature based on the p 2 o 5 and sio 2 concentrations in the aplites and the solubility of apatite in silicate melts apatite began to crystallize at 820 c in the aplites which also yields an estimate of 0 02 molal for the concentration of hcl for the blrc system by the apatite method within error both models produce the some result

helium chronometry of apatite and titanite using nd yag laser heating we developed a technique for extracting 4he from apatite and titanite using laser heating that permits measurement of u and th and hence u th he ages on a single sample aliquot unlike direct laser heating quantitative he extraction and u th retention can be achieved when samples are indirectly laser heated to temperatures below their melting point resulting he ages are consistent with those obtained from conventional furnace heating of larger samples the major advantages of this technique include faster analysis and far lower more reproducible he blanks that permit single crystal analyses single crystal dating opens a variety of new avenues for u th he chronometry

the case against vast glaciation in valles marineris mars abstract the valles marineris of mars form the largest system of interconnected canyons in the solar system where morphological mineralogical and structural evidence of widespread glaciation has been recently reported however neither precipitation models nor global water budgets can account for such a colossal fill and the hypothesis has thus far remained unchallenged by additional scrutiny here we present the first thorough case against a valles marineris glaciation by describing new evidence that precludes the existence of a glacier most crucially we review high resolution imaging science experiment hirise images of chaos terrain in candor chasma previously interpreted as remnant glacial ice and identify layered boulder rich scarps bearing no similarity to scarps of massive ice in promethei terra or the north polar layered deposits we also find no significant differences in the structure morphology and composition of chaos terrain in candor and the chryse planitia region which suggests candor s chaos like chryse s is fractured highland terrain we also review several other key supports for the glacial hypothesis including the coincidence of an apparent glacial trimline with the water bearing mineral jarosite and the apparent presence of glacial features including kettle holes and sandur plains these too are found to have more plausible explanations with non glacial origins including tectonic reorganisation groundwater sapping and chaotic fracturing we conclude that the valles marineris glacial hypothesis is inconsistent with both observed morphology and our understanding of the ancient martian climate and we find no evidence to support its existence

origin of biotite apatite rich enclaves achala batholith argentina the achala batholith of argentina contains very unusual layered enclaves containing up to 30 apatite and 50 biotite in some layers this modal mineralogy produces bulk rock compositions that cannot represent liquids having as little as 29 sio2 and up to 8 p2o5 nor can the enclaves represent metasedimentary xenoliths because 1 none of the precambrian wall rocks has these compositions 2 none of the metasedimentary xenoliths present within the batholith shows any degree of transition to the mica apatite rich enclaves 3 the compositions and textures in the enclaves are inconsistent with metasediments 4 a geochronological study of zircon from an enclave gives an age of 368 2 ma the exact age of zircons in the granitic host rocks for these reasons we conclude that the enclaves are neither xenoliths of precambrian wall rocks nor restite of a precambrian source the identical age of the enclave and the host granites coupled with textural mineralogical and bulk rock characteristics of the enclaves indicates that the enclaves are magmatic segregations i e cumulates the f rich nature of the stubby shaped apatites and biotites indicates a high f content of the magma parental to the enclaves we infer that the viscosity of the melt was lowered sufficiently to allow cumulates to form in spite of the granitic composition of the melt

apatite fission track age correction and thermal history analysis from projected track length distributions abstract the frequency distribution of fission track lengths in an apatite reflects the mineral s thermal history since the time of its last crossing into the partial annealing zone paz apatite thermal history analysis based on confined track length measurements is an already well established tool in hydrocarbon exploration in a less direct though more easily accessible way the thermal history is also reflected in the frequency distribution of the projected lengths of tracks intersecting the apatite surface a mathematical description of the probability distribution of the projected length of surface tracks ptld projected track length distribution corresponding to different types of thermal history is presented and a new method for correcting thermally lowered fission track ages is proposed this correction method gives the time of entry into the paz at 120 c but also the time when the sample left the paz to enter the total track stability zone at 60 c an age function is subsequently defined which allows us to distinguish between different types of thermal history experimental verification shows that although the proposed approach is less precise compared to existing methods based on projected track lengths it is possible to distinguish between different thermal histories provided that a sufficient number of tracks are measured on the other hand the age function provides information relative to the samples complete trajectory through the paz whereas existing methods are limited to temperatures below the closing temperature of the fission track system

geochemical contrasts between late triassic ore bearing and barren intrusions in the weibao cu pb zn deposit east kunlun mountains nw china constraints from accessory minerals zircon and apatite the weibao copper lead zinc skarn deposit is located in the northern east kunlun terrane nw china igneous intrusions in this deposit consist of barren diorite porphyry u pb zircon age of 232 0 2 0 ma and ore bearing quartz diorite and pyroxene diorite u pb zircon ages of 223 3 1 5 and 224 6 2 9 ma respectively whole rock major and trace element and accessory mineral zircon and apatite composition from these intrusions are studied to examine the different geochemical characteristics of ore bearing and barren intrusions compared to the barren diorite porphyry the ore bearing intrusions have higher ce4 ce3 ratios of zircon and lower mn contents of apatite indicating higher oxidation state besides apatite from the ore bearing intrusions shows higher cl contents and lower f cl ratios these characteristics collectively suggest the higher productivity of ore bearing quartz diorite and pyroxene diorite when compared with ore bearing intrusions from global porphyry cu deposits those from cu pb zn skarn deposits display lower ce4 ce3 and eun eun ratios of zircon and lower cl and higher f cl ratios of apatite we conclude that these differences reflect a general geochemical feature and that zircon and apatite composition is a sensitive tool to infer economic potential of magmas and the resulting mineralization types in intrusion related exploration targets

apatite chemical composition determined by electron microprobe and laser ablation inductively coupled plasma mass spectrometry as a probe into granite petrogenesis abstract major minor and trace element abundances in apatites from various i and s type igneous and sedimentary granites of the lachlan fold belt have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometer the results show that apatite can accommodate many minor and trace elements whose concentrations and ratios are relatively sensitive to factors controlling many of the fundamental differences between i and s type granites apatites from s type granites generally have higher f but lower cl contents than those from i type granites which is ascribed mainly to the loss of cl during the weathering processes forming the source rocks of s type granites although fractional crystallisation can cause significant enrichment in f as well high mn and fe contents in apatites from s type granites and high s and as abundances in apatites from mafic i type granites result from different oxygen fugacities and degrees of al saturation or aluminosity between metaluminous mafic i type magmas and peraluminous s type and felsic i type magmas there are systematic and distinctive differences in absolute rare earth element ree abundances ree distribution patterns and element ratios e g la y sm nd etc between apatites from different types of granite the strong eu depletion that characterises apatites from s and felsic i type granites is interpreted here to be a result of the uniqueness of crystal chemistry of apatite and high eu2 eu3 ratios in s type and felsic i type magmas which are more reduced and peraluminous than mafic i type magmas strong ree la to eu and th enrichment in apatites from mafic i type granites and marked nd depletion in apatites from most s type and felsic i type granites are caused by the precipitation and fractionation of monazite in the parental magmas of the latter rocks substitution mechanisms are responsible for high na in apatites from s type and felsic i type granites and for high si in apatites from mafic i type granites and may also have important effects on ree partitioning between apatite and melt thus apatite chemistry can be used as an excellent indicator of granite petrogenesis the results have important implications for identifying different types of granite and are potentially significant for determining the provenance of sedimentary rocks

investigations of the stillwater complex part v apatites as indicators of evolving fluid composition variations in the f cl and oh contents of apatite are not constrained by crystal chemical factors in contrast to micas and amphiboles and thus changes in the abundance of these components provide an indicator of halogen fugacity variations and insights into the degassing history of igneous rocks microprobe analysis of intercumulus apatites from the stillwater complex reveal that cl rich apatites typically containing 6 0 wt cl occur throughout the lower 1 3 of the complex excluding the basal series a change from cl rich to more f rich apatite occurs within olivine bearing zone i ob i of the banded series the host zone of the platiniferous j m reef although apatite compositions are somewhat variable above the j m reef more f rich apatites predominante and typically contain 1 2 wt f and 3 0 wt cl the most f rich apatites occur in the uppermost exposed cumulates pristine apatites from coeval sills and dikes from below the complex and from the basal series are similarly f rich in all apatites the cl and f contents are lower in rocks affected by later metamorphic fluids rare earth element ree concentrations in chlorapatites show a marked peak in the olivine rich rocks of the j m reef and contain up to 2 wt ce2o3 la2o3 the trend of first increasing then decreasing cl f ratios with stratigraphic height is modeled by a vapor driven zone refining process occurring within the cumulate pile causing cl enrichment in the interstitial melt accompanied by degassing at the top of the magma chamber causing overall loss of cl from the magma as crystallization proceeded the abrupt change from cl rich to more f rich apatites within ob i is interpreted as the result of a breakdown of the cl rich zone refining front and mixing with cl poor supernatant melt any high temperature fluids that exsolved and circulated through the lower 1 3 of the complex must have been enriched in cl and could have transported ree and trace metals

complex mineral zoning patterns caused by ultra local equilibrium at reaction interfaces chemically zoned minerals are useful records of temporal variations in ambient conditions and bulk chemical composition of the fl uid from which the minerals precipitate in fl buffered systems zoning of mineral compositions is expected to refl ect directly the evolution of fl composition here we show that during rapid fl uid rock reactions ultra local equilibrium can form complex mineral zoning patterns even when the overall system is highly fl uid buffered we reacted cleaved calcite single crystals with aqueous arsenate phosphate solutions with molar ratios of as as p between 0 01 and 0 15 at 250 c and water saturated pressure we fithat complex zoning patterns and solid solution between hydroxylapatiteand arsenate bearing hydroxylapatite that pseudomorphically replaced calcite formed within hours and these zoning patterns were destroyed within days during secondary reactions we propose a two stage reaction process in the formation of the fi nal reaction product 1 on an hour time scale calcite is dissolved and replaced by compositionally heterogeneous apatite the thin reaction interface fllayer becomes extremely enriched in arsenic at an ultra local scale as the reaction removes phosphate faster than the interface fl uid can re equilibrate with the bulk fl uid 2 the heterogeneous apatite is replaced by homogeneous apatite that refl ects the bulk fl uid composition over a longer days time scale through interface coupled dissolution precipitation this paper highlights the complexity that can arise from ultra local fl uid composition variations due to rapid fl uid rock interaction in a short lived fl uid fl ow event for example during a seismic cycle subsequent interpretation of complex zoning patterns as refl ecting the evolution of bulk fl uid would be erroneous

phosphorus and the rare earth elements in felsic magmas an assessment of the role of apatite abstract the solubility of fluorapatite in 17 silica rich melts in the system na 2 o k 2 o al 2 o 3 sio 2 with and without cao or caf 2 was determined at 1 kbar water pressure and 750 900 c apatite saturation occurs at levels of dissolved p 2 o 5 ranging between 0 04 0 02 and 0 28 0 13 wt with only 4 values outside the 0 09 0 20 wt range the results demonstrate not only that apatite is a common liquidus phase in felsic melts but also that under most circumstances it remains in the residue during episodes of partial fusion of the crust given a solubility limit of 0 14 wt dissolved p 2 o 5 the mean of the experimental values a source containing as little as 0 05 p 2 o 5 must be 35 melted before apatite is lost from the residue and no longer buffers the melt p 2 o 5 concentration at the saturation value higher abundances of p 2 o 5 in the source postpone the loss of residual apatite to still higher degrees of melting and if the source p 2 o 5 content exceeds 0 14 wt apatite must be residual for all degrees of melting increasing in abundance as melting proceeds the generally secondary influence of apatite on the rare earth element ree patterns of melt and residue is most apparent when garnet and or amphibole is minor or lacking in the residue fractional crystallization of intermediate e g andesitic magmas toward felsic compositions invariably results in saturation in apatite and some consequent depletion of ree in the melt

evolution of hf and hcl activity in magmatic volatiles of the gold mineralized emerald lake pluton yukon territory canada we examine the halogen contents of biotite amphibole and apatite from four magmatic phases of the emerald lake pluton to document the evolution in composition of magmatic volatiles in this system and to determine if this evolution is consistent with the nature and distribution of weak gold mineralization in the pluton in general the variations in halogen compositions of hydrous minerals are greater between magmatic phases than within single magma batches and the abundance of chlorine decreases and fluorine increases in hydrous minerals during the evolution of the emerald lake pluton by applying the internally consistent thermodynamic database and mineral activity composition relationships that account for coupled site substitution we further employ biotite and apatite compositions as independent monitors of fluid composition most analyzed biotite exhibits textural and or compositional features characteristic of late subsolidus halogen exchange with fluid however we have identified biotite that appears to retain halogen contents indicative of magmatic conditions fluorine contents of these biotites range from around 1 5 syenite and monzonite to greater than 2 2 wt in a late stage pegmatite dike chlorine by contrast shows a more restricted range of values and typically falls between 1 0 syenite and monzonite and 0 6 wt pegmatite apatite inclusions within anhydrous phenocrysts have fluorine contents of around 3 3 syenite to greater than 3 7 wt granite while chlorine contents fall from 0 5 to 0 1 wt with evolution from syenite to granite phases of the pluton the fluid a hcl a hf conditions recorded by biotite and apatite are in close agreement these two independent measures of hcl and hf both show a modest decrease in hcl hf as the system evolves the highest log a hcl a hf values 0 6 to 0 3 are associated with magmatic volatiles of syenite the first phase to intrude at emerald lake activity ratios recorded from the second phase monzonite show a slight fall to 0 4 to 0 1 a similar drop is recorded in the transition to hydrothermal activity recorded in biotite from a late pegmatite dike 0 1 to 0 1 a decrease in log a hcl a hf is consistent with a loss of chlorine and residual enrichment of fluorine in the magma due to progressive release of a chlorine bearing metalliferous fluid the relatively small variation in inferred fluid hcl and hf activity suggests that the magmatic volatiles present during crystallization were relatively homogeneous and argues against both the incursion of external fluids and of substantial temporal variation in fluid composition from the magma source furthermore if magmatic volatiles are the source of the gold mineralization found across all phases of the emerald lake pluton as advocated by other workers our data would suggest that the mineralizing fluids were remarkably homogeneous and distributed throughout the pluton the disseminated and low grade nature of mineralization may be at least in part a consequence

fluorine as a tool in the petrogenesis of quartz bearing magmatic associations applications of an improved f oh biotite apatite thermometer grid abstract fluorine contents of whole rock and biotites allow to discriminate quartz bearing magmatic associations through the nature of protoliths and petrogenetic processes f and rb are used to discriminate crustal and mantle derived melts with the exception of calcalkaline association in which mantle contribution may be significant the other quartz bearing associations are essentially derived from crustal melting by biotite and or amphibole vapor absent reactions based on experimental data and on an improved biotite apatite thermometer grid closure temperatures from near liquidus to near solidus conditions as well as fh2o fhf evolution during cooling are determined for the different magmatic associations it appears that the liquidus temperature and fh2o fhf decreases in the order high silica alkaline high k calcalkaline and calcalkaline associations while the solidus temperature follows an inverse order the fh2o fhf values for the peraluminous associations vary over a wide range and overlap the fh2o fhf values of the high k calcalkaline and calcalkaline associations

apatite in the dike gabbro transition zone of mid ocean ridge evidence for brine assimilation by axial melt lens we present textures and halogen and trace element compositions of apatites in intrusive rocks from the dike gabbro transition zone of a fast spreading mid ocean ridge which was formed at the east pacific rise and recently drilled by iodp hole 1256d these data are used to discuss the properties of parental magmas and seawater derived hydrothermal fluids at the roof of the axial melt lens during the formation of oceanic crust in general zoning of apatites from three different lithologies tonalites diorites and gabbros is common and shows a consistent evolution trend with depletion in cl and rees from core to rim the cores are usually homogenous in composition and interpreted as magmatic origin whereas zones with lower cl and rees are disseminated with heterogeneous concentrations indicating exchanges with hydrothermal fluids the apatite cores in tonalites are rich in both f and cl with x ap f proportion of fluorapatite end member up to 0 5 and x ap cl proportion of chlorapatite end member up to 0 4 in contrast the apatite cores in gabbros have high x ap cl up to 0 85 and very low x ap f s in some parts of the apatite crystals mainly rim can be explained by removal of these components via hydrothermal fluids based on available f cl oh exchange coefficients for apatite melt the very high cl oh and cl f ratios and high cl contents calculated for tonalitic melts cannot be reconciled with a formation of these felsic melts by partial melting of amphibole bearing metabasalts but indicate that an assimilation of high cl brines must have occurred similarly the low f chlorapatites in gabbros also imply an assimilation of high cl brines the source of high cl fluids in the axial magmatic system may result from seawater derived fluids which may form immiscible vapor and brine at high temperatures as a result of hydrothermal boiling

inter and intra crystal ree variations in apatite from the bob ingersoll pegmatite black hills south dakota abstract concentrations of rare earth elements ree have been measured on a suite of apatite crystals from an internally zoned granitic pegmatite enriched in li b be f nb ta sn and u with a cameca ims 3f ion microprobe using energy filtering an apatite specimen from the tin mountain pegmatite analyzed previously by isotope dilution was used as a standard the chondrite normalized pattern determined with the ion microprobe closely matches the pattern determined by isotope dilution with maxima at sm and dy and minima at nd and er apatite samples from the bob ingersoll pegmatite show a large range of ree patterns and concentrations in one case apatite crystals within millimeters show differences in ree concentrations and pattern shapes including a switch from positive to negative eu anomalies samples from several mineral assemblages show patchy individual crystal zoning with respect to the ree that is not mirrored by major element zoning this indicates disequilibrium conditions on a small scale consistent with rapid growth from a melt fluid system that was either of locally heterogeneous melt structure or in which the melt structure fluctuated rapidly as volatile rich minerals such as tourmaline crystallized these effects may be coupled with non ideal partitioning of ree in a heterogeneous mixture of melt aqueous fluid and crystals ree concentrations in apatite samples from the different pegmatite zones indicate a large variation in outer zones 10 500x chondrite high concentrations 100 1000x chondrite near the pegmatite core and very low concentration in the core 2 20x chondrite patterns are flat to slightly inclined ce yb 1 to 5 and most samples have positive eu anomalies the magnitude of positive eu anomalies decreases with inward position in the pegmatite possibly indicating a progressive increase in o 2 and a sharp increase may be indicated by systematic ce depletion in apatite from the pegmatite core ree specific volatile complexes may contribute to variations including unusual kinks observed in ree patterns of apatite from mineral assemblages in upper parts of the pegmatite

parsimonious migration of 3 c 3d vsp data conventional kirchhoff migration can be made much faster by a priori calculation of wave arrival directions and tracing rays back only along the measured directions this is known as parsimonious migration for surface seismic data where acquisition with 2d arrays is common the wave arrival directions can be measured by using local slant stacking to calculate the two horizontal slowness components the vertical slowness is then deduced by using the dispersion relation for vertical seismic profile vsp data where multiline acquisition is not possible only the vertical component of the slowness vector can be measured which is insufficient to constrain the wave arrival direction we overcome this limitation for three component vsp data by polarization analysis of the incident waves polar and azimuth anglesare calculated at the receivers by estimating the data covariance matrix and the vertical slowness assuming isotropic media and linear polarization of both p and s waves for p waves the data co

the geochemistry of apatite from the los colorados iron oxide apatite deposit chile implications for ore genesis apatite grains from the los colorados iron oxide apatite ioa deposit the largest ioa deposit in the chilean iron belt cib exhibit significant intracrystalline spatial variability with respect to the concentrations of f cl and oh and trace elements statistical interrogation of the compositional data indicates that individual apatite grains contain spatially discrete f rich and cl rich domains the chemical composition of the f rich domains is consistent with apatite growth from silicate melts whereas the chemical composition of the cl rich domains is consistent with apatite growth from a magmatic hydrothermal fluid that cooled as it percolated outward from the los colorados fault the structural control for emplacement of the ore body into the surrounding brecciated diorite and andesite host rocks apatite in the deposit is intimately intergrown with magnetite and actinolite for which trace element fe h and o stable isotope data indicate a combined magmatic magmatic hydrothermal genesis for the deposit the compositional data for apatite are consistent with a genetic model wherein f rich apatite cores crystallized with magnetite from silicate melt followed by exsolution of a magmatic hydrothermal fluid during decompression of the parent magma experimental studies demonstrate that magmatic hydrothermal volatile phase bubbles preferentially nucleate and grow on the surfaces of apatite and magnetite microlites during decompression of a magma body continued degassing of the melt results in the volatile phase sweeping up apatite and magnetite microlites and forming a magnetite apatite fluid suspension that is buoyant in the magma chamber and ascends from the source magma along faults during regional extension halite saturated fluid inclusions in magnetite which is paragenetically equivalent to apatite at los colorados indicate that the magmatic hydrothermal fluid was a brine which allows this fluid to efficiently scavenge cl p rare earth elements and other fluid compatible elements from the silicate melt during ascent the xcl xf ratio of apatite increases as it grows from the evolving cl rich magmatic hydrothermal fluid during decompression and cooling

accessory mineral chemistry as a monitor of petrogenetic and metallogenetic processes a comparative study of zircon and apatite from wushan cu and zhuxiling w mo mineralization related granitoids abstract in this study we explore the chemistry of accessory apatite and zircon as tools to monitor the petrogenetic and metallogenetic processes involved in the formation of the wushan cu and zhuxiling w mo mineralization related granodiorite porphyry the wushan granitoids are metaluminous with a cnk of 0 88 1 01 and the zhuxiling intrusions are weakly peraluminous with higher a cnk values 1 02 1 12 the wushan granitoids have end t values of 4 6 to 4 7 which combined with the relatively elevated mg values 57 62 and adakitic features high sr y ratios of 51 60 indicate that they were derived from melting of a thickened lower crust of the yangtze block with addition of small amounts of mantle components compared to the wushan granitoids the zhuxiling granitoids have relatively high 87sr 86sr i 0 70945 0 70951 and low end t values 5 9 to 6 3 and zircon ehf t values 3 8 to 9 0 suggesting their derivation dominantly from partial melting of the neoproterozoic crust the apatites from the zhuxiling samples are characterized by relatively high mno and feo variable y and low ce which is consistent with the weakly peraluminous feature of whole rock chemistry these apatites show notable depletion of th and lree with a lower la sm n ratio 0 74 1 44 and la yb n ratio 6 2 17 9 relative to those of the host rock 3 04 3 61 and 19 1 23 4 respectively suggesting early crystallization of some lree and th enriched minerals such as allanite monazite before apatite crystallization the steep trend of ce sm versus yb gd ratios shown by zircons from the zhuxiling granitoids suggests that the crystallization of zircon is affected by the crystallization of titanite and apatite thus the crystallization sequence of accessory minerals in the zhuxiling intrusion is allanite apatite titanite and zircon the apatites from the wushan granitoids however show strongly lree enriched ree patterns with weak negative eu anomalies which indicate minor feldspar fractionation and mildly magmatic differentiation the flat trend of ce sm versus yb gd ratios shown by zircon from the wushan pluton indicates that its ree composition is affected by hornblende saturation zircon grains from the metaluminous wushan granitoids exhibit remarkably higher ce4 ce3 ratios and weaker eu eu anomalies than those of the peraluminous zhuxiling samples and the apatites from the wushan samples show higher eu eu 0 55 0 62 and lower ce ce 0 91 1 04 and mno 0 05 0 09 compared to those of the zhuxiling pluton with eu eu 0 41 0 50 ce ce 1 06 1 11 and mno 0 15 0 18 respectively the apatite and zircon chemistry suggest that the cu bearing granitoid formed at an oxygen fugacity higher than the w bearing granitoid which agrees with the fact that the wushan granitoids show whole rock fe3 fe2 ratios higher than the zhuxiling granitoids in addition apatites from the wushan intrusion show enrichment of cl and higher f cl ratios compared to those of the zhuxiling samples suggesting that a water rich parental magma with relatively high cl content is favourable for copper mineralization this case study shows that apatite and zircon chemistry could reflect the geochemical characteristics of their host rock and magma evolution moreover they provide insights into the oxidation state halogen fugacity and magma differentiation of the magmatic system which are key factors for mineralization our data suggest that magma associated with cu mineralization is relatively oxidizing chlorine enriched and less fractionated compared to w bearing magma

behaviour of apatite during partial melting of metapelites and consequences for prograde suprasolidus monazite growth abstract the suprasolidus behaviour of apatite and monazite is examined for an average metapelite composition using phase equilibria modelling coupled with solubility equations of these minerals both closed and open system scenarios are considered partial melting above the solidus requires apatite and monazite breakdown in order to saturate the anatectic melt in phosphorus and the light rare earth elements in general melt loss is predicted to increase the stability of apatite and monazite at high temperature most apatite is predicted to survive up to ultrahigh temperature conditions except for rocks with low bulk phosphorus concentrations by contrast most monazite is expected to be consumed by uht conditions thorium substitution in monazite is expected to increase the stability of monazite to higher temperatures the presence of lree rich apatite decreases the stability of monazite above the solidus but the breakdown of this apatite during anatexis may generate prograde monazite at the apatite melt interface in local pockets of melt oversaturation however prograde suprasolidus monazite along grain boundaries is expected to be consumed during further partial melting or during melt homogenization when an interconnected melt network develops anatectic melts are predicted to be saturated with respect to apatite except at uht conditions and for rocks with low initial p2o5 bulk concentrations

crystallization of apatite in natural magmas under high pressure hydrous conditions with particular reference to orogenic rock series two separate series of hydrous experiments involving 1 imposing apatite saturation on a series of igneous rock compositions from basanite to rhyolite and 2 crystallizing similar natural rock compositions progressively until apatite appears demonstrate a close dependence between apatite saturation and silica content of the magma and determine p2o5 levels at a given silica value and temperature at which that composition may be expected to crystallize apatite the effect of pressure on apatite solubility is not great and is most significant for silicic compositions

hydrothermal apatite sims th pb dating constraints on the timing of low temperature hydrothermal au deposits in nibao sw china abstract precise geochronology is a crucial tool for understanding the genesis of low temperature hydrothermal mineral deposits but datable minerals are not always available e g mineralization within sedimentary rocks such as carlin type or carlin like au deposits here we demonstrate that hydrothermal apatite associated with au from the large nibao deposit in the yunnan guizhou guangxi region of south china can be dated to yield the age of au mineralization nibao is a carlin like deposit hosted in a permian carbonate bearing pyroclastic breccia the auriferous minerals are predominantly zoned pyrite containing as cu and au rich rims euhedral and subhedral apatite forms a mosaic texture and is intergrown with hydrothermal quartz sericite and zoned auriferous pyrite indicating that the apatite is of hydrothermal origin and was coeval with au mineralization unlike sedimentary and igneous apatite hydrothermal apatite is relatively depleted in lrees enriched in mrees and slightly depleted in eu hydrothermal apatite also has high th u ratios negligible u concentrations and very low concentrations of common pb this makes the apatite a potential candidate for th pb dating our sims th pb analyses yield a weighted mean 232th 208pb age of 141 3 ma n 23 mswd 2 2 for apatite coeval with auriferous pyrite and this is the best estimate of the timing of au mineralization hydrothermal apatite is also present in similar deposits in the golden triangle of south china therefore th pb dating of hydrothermal apatite potentially allows for the accurate dating of low temperature hydrothermal deposits in china and worldwide

coupled substitutions involving rees and na and si in apatites in alkaline rocks from the ilimaussaq intrusion south greenland and the petrological implications ansrnlcr apatites from the ilimaussaq augite syenite the sodalite foyaite and a qtartz bearing peralkaline pegmatite have been analyzed using an electron microprobe for the major elements plus na si and selected rare earth elements rees in all three rock types the maximum reeto3 content in the apatite exceeds 16 0 wt0 0 apatite from the augite syenite and primary apatite from the sodalite foyaite are characterizedby a low na content that varies independently of the ree content the composition of these apatites approaches 25 molo o of the end member carreq sio4 3 oh f cl lessingite in response to the substitution ree3 sia ca2 ps ree and na enriched apatites from the quartzbearing peralkaline pegmatite are almost si free and rees and na are positively correlated the composition of these apatites approaches 25 molo o of the hypothetical endmember na5ree5 po4 6 oh f ci 2 in response to the substitution na ree3 2ca2 the compositional trend of late crystalllzing apatite from the sodalite foyaite reflects almost equal contributions of the two substitutions the relationship between these substitutions in a given apatite and its associated mineral assemblage indicates that the na component is only present in considerable amounts when apatite crystallizes in a strongly peralkaline environment

apatite in felsic rocks a model for the estimation of initial halogen concentrations in the bishop tuff long valley and tuolumne intrusive suite sierra nevada batholith magmas

orientation of a downhole triaxial geophone the bearing and elevation of a geophone s axes are unknown when a geophone package is placed in a deep exploration borehole auxiliary instruments such as inclinometers compasses or gyros may be incorporated into the downhole package to give some indication of local attitude relative to some external reference field but these solutions may encounter difficulties because small gyros drift the geomagnetic field may be distorted locally or screened by casing and inclinometers add to the cost and weight of the downhole receiver an alternate approach to determining the orientation of a remote tool is to compare its triaxial response to that expected for a known elastic wavefield the accuracy of the measurement depends on the quality of the geophone to formation coupling and on the extent of one s knowledge of the externally impressed wavefield

experimental silicate phosphate equilibria in peraluminous granitic magmas with a case study of the alburquerque batholith at tres arroyos badajoz spain with the actual mineralogy and whole rock p in the granite experimental results presented here establish the p2o5 content of aplite pegmatite facies at tres arroyos peraluminous silicic melt for three potential buffering reactions at 200 mpa h2o and t from 525 to 850 c 1 biotite sarcopside 2 spessartine sarcopside 3 petalite amblygonite montebrasite quartz the first two equilibria are moderately insensitive to t and buffer the p content of melt between 1 30 1 57 wt

the source of phosphate in the oxidation zone of ore deposits evidence from oxygen isotope compositions of pyromorphite abstract pyromorphite pb5 po4 3cl is an abundant mineral in oxidized zones of lead bearing ore deposits and due to its very low solubility product effectively binds pb during supergene alteration of galena pbs the capacity of a soil or near surface fluid to immobilize dissolved pb depends critically on the availability of phosphate in this soil or fluid potential phosphorus sources in soil include i release during biological processes i e leaching from litter lysis of microbial cells after intracellular enzyme activity in soil and hydrolysis from soil organic matter by extracellular enzymes and ii inorganic phosphate from the dissolution of apatite in the adjacent basement rocks intracellular enzyme activity in plants microorganisms associated with kinetic fractionation produces an oxygen isotope composition distinctly different from inorganic processes in soil this study presents the first oxygen isotope data for phosphate 18op in pyromorphite and a comprehensive data set for apatite from crystalline rocks we investigated 38 pyromorphites from 26 localities in the schwarzwald southwest germany and five samples from localities outside the schwarzwald in addition to 12 apatite separates from gneissic and granitic host rocks pyromorphites had 18op values between 10 and 19 comparable to literature data on 18op in the readily available p fraction in soil resin extractable p from which minerals potentially precipitate in soils 18op values below the range of equilibrium isotope fractionation can be attributed either to apatites that formed geochemically 18op of apatites 6 to 9 or less likely to biological processes extracellular enzyme activity however for most of our samples isotopic equilibrium with ambient water was indicated which suggests biological activity therefore we conclude that the majority of pyromorphites in oxidized zones of ore bodies formed from biologically cycled phosphate this study highlights that biological activity and pb mobilization are intimately connected in humid regions with high biological activity in soil pb might be precipitated rapidly due to biologically released phosphate whereas pb will be released to the environment from ore deposits or mine dumps much more easily in arid regions with low biological activity because pyromorphite cannot form due to limited supply of phosphorus

the solubility of apatite in h 2 o kcl h 2 o nacl h 2 o at 800 c and 1 0 gpa implications for ree mobility in high grade saline brines abstract apatite is an important host for lree f and cl and thus can be used to monitor elemental mass transfer in high p t settings in this investigation the solubilities of synthetic fluor and chlorapatite and natural durango fluorapatite were measured in h2o kcl h2o and nacl h2o fluids at 800 c and 1 0 gpa using the piston cylinder apparatus the solubility of apatite is reported in parts million by weight ppm and is calculated via the formula map map h2o kcl or nacl map 106 where map map in map out the experimental results indicate a strong increase in apatite solubility in aqueous fluids with moderate kcl and nacl mole fractions xkcl and xnacl under all conditions synthetic fluorapatite and synthetic chlorapatite dissolve congruently the solubility of synthetic fluorapatite increases from 19 ppm in pure h2o to 2123 ppm at xkcl 0 52 the solubility of synthetic chlorapatite rises from 37 ppm in pure h2o to 2590 ppm at xkcl 0 50 at xkcl 0 5 the solubility of synthetic fluorapatite decreases to 1691 xkcl 0 72 and the solubility of synthetic chlorapatite decreases to 2284 ppm xkcl 0 65 in contrast natural durango fluorapatite dissolves incongruently at xkcl 0 2 the solubility of natural durango fluorapatite increases from 70 ppm in pure h2o to 2073 ppm at xkcl 0 50 respectively in contrast to the kcl h2o system apatite solubilities are considerably higher in the nacl h2o system the solubility of synthetic fluorapatite increases to 4909 ppm at xnacl 0 51 and the solubility of synthetic chlorapatite rises to 5144 ppm at xnacl 0 50 compared to fluorite calcite and anhydrite apatite solubility is significantly lower in h2o nacl h2o and kcl h2o after completion of each experiment the ph was measured and a comprehensive step by step procedure limiting reactant concept was used to model the observed quench ph in the system apatite kcl h2o

tracing fluid saturation during pegmatite differentiation by studying the fluid inclusion evolution and multiphase cassiterite mineralisation of the gatumba pegmatite dyke system nw rwanda abstract aqueous fluid saturation during the internal evolution of phosphorus and boron rich pegmatites in nw rwanda has been investigated using petrography fluid inclusion microthermometry and microanalysis of minerals and fluid inclusions raman microspectroscopy and la icp ms the gatumba dyke system gds in rwanda has been selected for this study because it hosts a multiphase cassiterite mineralisation in wall core and internal replacement zones suggesting an advancing influence of magmatic hydrothermal conditions during dyke solidification as such multiphase cassiterite precipitation is applied as a tracer for magmatic to hydrothermal crystallisation processes in granitic pegmatites the gds consists of a group of six major lct lithium caesium tantalum family dykes which all belong to the most differentiated rare element pegmatites in the gatumba gitarama field petrography identified a well developed internal anatomy consisting of a border wall intermediate and a quartz core zone in addition replacement zones developed as cleavelandite after perthitic microcline units in the intermediate zone and as muscovite quartz pockets in the intermediate and wall zones the latter replacement zone display muscovitisation reactions with the formation of greisens texturally the greisen pockets replace the secondary cleavelandite units during internal differentiation multiphase cassiterite mineralisation formed in 1 large microcline crystals of the wall zone cst1 2 assemblage with quartz f poor montebrasite and carbonate and boron enriched mn fluorapatite in the core zone cst2 and 3 the greisen replacement units in the wall and intermediate zones cst3 fluid inclusion micro analyses demonstrate that a saline aqueous h2o nacl kcl co2 n2 l1 type fluid 20 wt nacl and 3 wt kcl was saturated during onset of crystallisation of the wall and intermediate zones and precipitation of the disseminated magmatic hydrothermal cst1 mineralisation in and around large perthitic k feldspars isochore reconstructions of this l1 fluid indicate crystallisation conditions of 535 560 c and 5 1 5 6 kbar for the gds extensive microcline fractionation and subsequent replacement reactions of cleavelandite after microcline in the intermediate zone were induced by a li enriched and more na depleted h2o nacl licl co2 n2 l2 type fluid which was present during solidification of the core zone and present during precipitation of cst2 phase mineralisation 6 12 wt nacl 1 10 wt licl late stage hydrothermal cst3 mineralisation in the greisen pockets precipitated from a cs enriched h2o nacl kcl co2 n2 l3 type fluid 15 wt nacl distinctly after the formation of the cleavelandite replacement units subsolidus cst3 precipitation is dominantly driven by metasomatic hydrolytic fluid rock reactions combining textural microthermometric and fluid compositional data with reported sn melt fluid partitioning and solubility data demonstrate that primary cassiterite i e cst1 and cst2 in the wall and core zone of the gds precipitated from the exsolved saline aqueous l1 and l2 fluid present at the interface of the highly fractionated melt phase fast disequilibrium growth of near anhydrous mineral assemblages likely caused the formation of flux rich and at least locally water saturated melt compositions at the crystallisation front of the large crystals this study emphasises the importance of local magmatic hydrothermal conditions and the presence of an immiscible aqueous fluid phase during the internal crystallisation and cassiterite mineralisation of rare element pegmatites

l apatite de durango mexique analyse d un mineral standard pour la datation par traces de fission abstract durango apatite is analyzed by four analysts using three different dating techniques both the annealing technique and the external detector technique are applied to basal and prismatic sections cut from single crystals the population technique is applied to mounts of randomly oriented grains provided an individual determination of the geometry factor is performed all ages are indistinguishable from the reference age of 31 4 0 5 ma there is no noticeable influence of either the dating technique or the crystallographic orientation of the dated section on the ft age based on the projected lengths of surface tracks spontaneous track length reduction varies from 4 to 10 mean 6 depending on the analyst two simple corrections are applied to eliminate the net effect of the missing short tracks on the mean projected length after correction the amount of shortening of the spontaneous tracks is found to be slightly larger mean 8 but is still dependent on the analyst 4 to 12 the mean is in fairly good agreement with the value obtained from confined track length measurements 9 finally an isochronal 1 h plateau annealing procedure was applied to a separate set of basal and prismatic sections cut from the same single crystals annealing temperatures up to 300 c do not affect the ft age erratic ages at 350 c are ascribed to the occurrence of unetchable gaps it is argued that the absence of a distinct plateau up to temperatures where it could be expected from theoretical considerations indicates that the ft age of durango apatite needs no correction

apatite dissolution into peraluminous haplogranitic melts an experimental study of solubilities and mechanisms apatite ap dissolution and solubility in the peraluminous haplogranite system were investigated in three sets of experiments at 750 c and 200 mpa ph2o as functions of ap grain size abundance melt ap ratio and melt asi alumina saturation index mol al2o3 na2o k2o cao between an asi of 1 1 1 metaluminous to mildly peraluminous the solubility of ap as measured by p2o5 in the melt is low 0 1 wt p2o5 which agrees with previous work in equilibrium runs with more strongly peraluminous compositions however ap solubility increases linearly with asi to p2o5 0 63 wt in melt at asi 1 3 and can be denned by a simple equation p2o5 3 4 3 1 asi r 0 833 which agrees within error with previous calculations reported in the literature in experiments where ap grains are sparce and widely separated i e simulating ap distribution in an ap bearing peraluminous protolith undergoing anatexis the dissolution of ap involves transient disequilibrium that promotes higher solubility of p2o5 up to nearly six times the equilibrium values adjacent to ap at a given bulk asi of melt and this increases the al si of melt in the ap dissolution aureole the approach to equilibrium between ap and melt is hastened by increasing the ap melt ratio within the local melt pool e g the capsule or by decreasing ap grain size for a similar melt ap ratio diffusivity calculations using inverse error function methods for the normal diffusion of p and ca yield dp 10 11 cm2 s and dca 10 10 cm2 s confirming prior results that diffusion of p away from ap surfaces is the rate limiting factor in ap dissolution these results combined with previous work at higher temperatures but on similar hydrous melts yield an activation energy e for p diffusion of 16 5 kcal mol and a frequency factor d0 of 1 4 10 3 cm2 s phosphorus diffusion through the melt is accompanied by uphill diffusion of al resulting in an increase of up to 2 wt al2o3 in melt near the ap within the ap dissolution aureole melt contains one additional al cation for every p cation i e al p 1 1 which is suggestive of an associated alpo4 complex the exchange reaction in melt is represented by alpsi 1 in which 2 to4 clusters are created in the place of 1 this exchange should be accompanied by discernable changes in melt properties e g density molar volume viscosity the results have applications to equilibrium and local disequilibrium effects during anatexis of apbearing metapelites and to the saturation limits of ap during crystallization of peraluminous magmas the dissolution of flux bearing minerals such as ap e g those containing p b or f may influence the stability and solubility of other trace element bearing minerals during anatexis of metapelites texture e g grain size and distribution and spacial relationship to other minerals plays an important role in reaction kinetics and at least temporarily in mineral solubilities the disequilibrium behavior of accessory minerals has critical consequences for ree modelling of granites

two methods for determining geophone orientations from vsp data vertical seismic profile vsp data are usually acquired with three component geophones of unknown azimuthal orientation the geophone orientation must be estimated from the recorded data as a prerequisite to processing such as p and s wave separation calculation of wave incident directions and 3d migration we compare and combine two methods for estimating azimuthal orientation by least squares fitting over a large number of shots combining the two methods can be done in an automated manner which provides more accurate estimates of the geophone orientations than previous methods in the polarization plane method we calculate the polarization plane of the first p wave arrival then we subtract the source azimuth to determine the geophone orientation independently for each geophone with an angular uncertainty of and with no accumulated errors in the relative angle method we obtain relative angles between adjacent geophone pairs using trace crosscorrelations and operate on all coherent signal

three component sonde orientation in a deviated well in well seismics when operating with a three component tool particle velocities are measured in the sonde coordinate system but are often needed in other systems e g source bound or geographic when the well is vertical a change from the three orthogonal components of the sonde to another orthogonal coordinate system can be performed through one rotation around the vertical axis and if necessary another one around a horizontal axis hardage 1983 if the well is deviated the change of coordinate system remains easy in the case when the source is located at the vertical of the sonde or in the case when the source stands in the vertical plane defined by the local well axis in the general case offset vsps or walkaways or when looking for unknown sources such as microseismic emissions induced by hydraulic fracturing coordinate rotation may still be performed provided that we first get back to a situation in which one of the axes is vertical

ore genesis and fluid evolution of the qiaomaishan cu w deposit in the middle lower yangtze river metallogenic belt evidence from in situ analyses of apatite and scheelite abstract the newly exploited qiaomaishan skarn type cu w deposit located in the xuancheng ore cluster district in the middle lower yangtze river metallogenic belt mlyrb is one of the few tungsten polymetallic deposits in this region this study conducted a series of in situ analyses of elements and isotopes for apatite scheelites and sulfides aiming to provide new insights into the source hydrothermal ore forming processes fluid evolution history and genesis of this deposit and important knowledge to investigate regional tungsten mineralization events in the mlyrb apatite geochemistry shows that the early magma source of the ore related rocks in qiaomaishan obviously displayed adakitic affinity with high oxygen fugacity and featured fluorine rich fluids originating from a w rich mixed source the tungsten mineralization is dominated by scheelite in the qiaomaishan deposit based on microscopic observations and in situ analysis two types of scheelite with different geochemical characteristics were recognized two types of scheelite in the qiaomaishan have controlled by different mechanism of ree substitutions scheelite i occurs in the sulfide stage and displays high na and ree concentrations downwards sloping ree fractionation trends with negative eu anomalies and 87sr 86sr ratios 0 70945 0 71033 similar to those of ore related granodiorite porphyry however scheelite ii shows relatively low ree concentrations high na contents mree rich patterns with positive eu anomalies and high 87sr 86sr ratios 0 71477 0 72352 distinct eu anomalies and sr concentrations of the two types of scheelite and s isotopes of sulfides indicate that the early stage fluids were inherited from the primary granodioritic magmatic hydrothermal fluids however the late stage fluids were modified by intense fluid rock interactions and inputs from the host gypsum bearing carbonates collectively the f and w rich sources intense fluid rock interactions and changes in oxidation reduction conditions favoured tungsten mineralization which resulted in the formation of the qiaomaishan tungsten deposit

magma mixing in granitic rocks of the central sierra nevada california abstract the el capitan alaskite exposed in the north american wall yosemite national park was intruded by two sets of mafic dikes that interacted thermally and chemically with the host alaskite comparisons of petrographic and compositional data for these dikes and alaskite with published data for sierra nevada plutons lead us to suggest that mafic magmas were important in the generation of the sierra nevada batholith specifically we conclude that 1 intrusion of mafic magmas in the lower crust caused partial melting and generation of alaskite rhyolitic magmas 2 interaction between the mafic and felsic magmas lead to the observed linear variation diagrams for major elements 3 most mafic inclusions in sierra nevada plutons represent chilled pillows of mafic magmas related by fractional crystallization and granitoid assimilation that dissolve into their felsic host and contaminate it to intermediate granodioritic compositions 4 vesiculation of hydrous mafic magma upon chilling may allow buoyant mafic inclusions and their disaggregation products to collect beneath a pluton s domed ceiling causing the zoning mafic margins to felsic core that these plutons exhibit

a complex linear least squares method to derive relative and absolute orientations of seismic sensors summary determining the relative orientation of the horizontal components of seismic sensors is a common problem that limits data analysis and interpretation for several acquisition setups including linear arrays of geophones deployed in borehole installations or ocean bottom seismometers deployed at the seafloor to solve this problem we propose a new inversion method based on a complex linear algebra approach relative orientation angles are retrieved by minimizing in a least squares sense the l2 norm between the complex traces hodograms of adjacent pairs of sensors this methodology can be applied without restrictions only if the wavefield recorded by each pair of sensors is very similar in most cases it is possible to satisfy this condition by low pass filtering the recorded waveforms the main advantage of our methodology is that in the complex domain the relative orientations of seismic sensors can be viewed as a linear inverse problem which ensures that the preferred solution corresponds to the global minimum of a misfit function it is also possible to use simultaneously more than one independent data set other seismic events to better constrain the solution of the inverse problem furthermore by a computational point of view our method results faster than the relative orientation methods based on waveform cross correlation after several tests on synthetic data sets we applied successfully our methodology to different types of real data these applications include the alignment of borehole sensors relative to a vertical seismic profiling vsp acquisition and the orientation of ocean bottom seismometers obs relative to a neighbouring land station of known orientation using land stations the absolute orientation of obs can be retrieved finally as a last application we checked the correct orientation for land stations of a seismological array in germany

factors controlling sulfur concentrations in volcanic apatite apatite crystals from two types of samples were analyzed by electron microprobe for 15 major and trace elements 1 apatite in h2o and s saturated experimental charges of the 1982 el chichon trachyandesite and 2 apatite in volcanic rocks erupted from 20 volcanoes the so3 contents of the experimental apatite increase with increasing oxygen fugacity from 0 04 wt in reduced charges buffered by fayalite magnetite quartz o2 fmq to 1 0 2 6 wt in oxidized charges buffered by manganosite hausmanite mnh or magnetite hematite mth the so3 contents of mnh and mth buffered apatite also generally increase with increasing pressure from 2 to 4 kbar and decreasing temperature from 950 to 800 8c the partition coefficient for so 3 between apatite and oxidized melt increases with decreasing temperature but appears to be independent of pressure apatites in volcanic rocks show a wide range of so3 contents 0 04 to 0 63 wt our sample set includes one group known to contain primary anhydrite and a second group inferred to have been free of primary anhydrite no systematic differences in apatite s contents are observed between these two groups our study was initiated to define the factors controlling s contents in apatite and to evaluate the hypothesis that high s contents in apatite could be characteristic of s rich anhydrite bearing magmas such as those erupted from el chichon in 1982 and pinatubo in 1991 this hypothesis is shown to be invalid probably chiefly a consequence of the slow intra crystalline diffusion that limits re equil ibration between early formed apatite and the evolving silicate melt contributing factors include early crystallization of most apatite over a relatively small temperature interval common late stage magmatic enrichment of s progressive oxidation during magmatic evolution and strong controls on s contents in apatite exerted by temperature and o2 pressure

granites of the batholiths of california products of local assimilation and regional scale crustal contamination we address on a regional scale the controversial problem of determining the source materials involved in the formation of the granites of southwestern north america compositional data on plutonic biotites whole rock chemistry and mineral assemblages in rocks collected as part of sampling traverses across die batholiths of central and southern california are assessed for this purpose we conclude that two distinct types of granites occur in california one type largely overlooked in the past and which we term i scr strongly contaminated and reduced i type is confined to narrow northwest striking belts in the western sierra nevada and peninsular ranges batholiths in prebatholithic continental margin terrenes containing reduced pelitic roof pendants we interpret the i scr magmas to have arisen from local scale contamination of i type magmas that intruded reducing pelitic material in sedimentary roof pendant terrenes we conclude that cordierite bearing s types are absent from the california batholiths although sedimentary materials were required to produce the i scr plutons the second type of granite which we refer to as i sc strongly contaminated but not reduced i type occurs on the eastern side of the california batholiths as part of a well known regional west to east progression from quartz diorites to granites these granites are the eastern variant of a sequence that is from west to east i wc weakly contaminated i mc moderately contaminated and i sc this eastward progression is not controlled by pendant occurrence and probably reflects increasing contamination on a regional scale of mantle i type magmas with f rich igneous and metamorphic rocks or their sedimentary derivatives of the precambrian continental craton we demonstrate that the nature of prebatholithic terranes can strongly influence the composition and regional distribution of granitic rocks developed in an active continental margin

apatite solubility in peraluminous liquids experimental data and an extension of the harrison watson model abstract new experimental data at 750 1000 c 2 5 kbar and for peraluminous melt compositions show a dramatic increase of apatite solubilities and phosphorus melt contents when compared to metaluminous or peralkaline compositions harrison and watson 1984 the formation of alumino phosphate units in peraluminous melts qualitatively explains our data a new apatite solubility model incorporating the data for the peraluminous region is presented application of this model to examples of peraluminous felsic suites is discussed

incongruent dissolution of ree and sr rich apatite in peraluminous granitic liquids differential apatite monazite and xenotime solubilities during anatexis the relative solubilities of monazite mnz xenotime xno and apatite ap ree and sr rich and ree and sr poor have been studied in peraluminous granitic liquids in month long experiments at 750 c and 200 mpa ph20 in contrast with the high solubility of the apatite 0 7 wtojop205 in strongly peraluminous liquids monazite and xenotime have much lower solubilities 0 05 wt jop205 in mildly to strongly peraluminous compositions p205 in the liquid is 0 03 0 04 wt joat xenotime saturation and 0 02 0 05 wt jo at monazite saturation in keeping with the low p in the glasses re203 contents are below emp detection thresholds 50 08 wt jo for all conditions of experiments saturation of liquid at equilibrium and local saturation around apatite apatite dissolves incongruently crystallizing ree rich monazite on its surface 1 4 m iong grains resulting in similar low ree contents in liquids monazite precipitation occurs along the margins of dissolving apatite crystals even though the bulk liquid is not monazite saturated the abundance of monazite microcrystals increases with the ree content of the apatite and the degree of apatite dissolution the reaction relationship ap liqi mnz liq2 stemming from differences in relative solubilities greater than an order of magnitude between apatite and monazite results in the dissolution of much smaller amounts of ree into peraluminous liquids than expected by simple evaluation of apatite ree contents the amount of ree contributed from apatite directly to peraluminous granitic liquid is related to the amount of apatite dissolved by simple mass balance only if the total ree content of the apatite is sufficiently low that monazite saturation in liquid 50 100 ppm re203 at 750 c is avoided during dissolution of sr rich apatite the sr partitions into the liquid and at 750 c and 200 mpa ph20 the diffusion coefficient of sr in liquid is 2 x 10 10 cm2js r2 0 659 the reaction relationships described above may have application to some textural features observed in natural igneous rocks for example clusters of monazite microcrystals might be indicators of dissolved apatite monazite morphology can be used to distinguish the source of its ree and the general petrological process rock anatexis or magma crystallization under which the monazite formed in addition monazite microcrystals could serve as nucleation sites for other minerals which might explain their common inclusion in biotite and amphibole within granitoids

using apatite to discriminate synchronous ore associated and barren granitoid rocks a case study from the edong metallogenic district south china abstract in order to find criteria to discriminate the synchronous ore associated and barren granitoid rocks we have determined apatite chemistry associated with ore associated cu au and barren granitoid rocks in the edong district of the middle and lower yangtze river metallogenic belt south china both rock types give zircon u pb ages between 135 0 and 138 7 ma apatite has a higher volatile and li content cl 0 19 0 57 wt average 0 35 wt so3 0 08 0 71 wt average 0 32 wt li 0 49 7 99 ppm average 3 23 ppm in ore associated rocks than those in barren rocks cl 0 09 0 31 wt average 0 16 wt so3 0 06 0 28 wt average 0 16 wt li 0 15 0 89 ppm average 0 36 ppm apatite la yb n ratios and eu eu values are relatively high and show wider variation in ore associated rocks than those in barren rocks apatite la sm n and yb sm n show positive correlation in ore associated rocks but negative in barren rocks the higher volatile content occurs in ore associated magma favoring cu au transportation and deposition furthermore amphibole fractional crystallization in ore associated magma further enriched the ore elements in the residual melt barren rocks may have undergone fluid exsolution before emplacement which makes it barren in cl s and ore elements cu s these signatures emphases the significance of volatile and magma evolution in mineralization and indicate that analyses of magmatic apatite can serve to distinguish ore associated from barren intrusions

partitioning of fluorine and chlorine between apatite and aqueous fluids at high pressure and temperature implications for the f and cl content of highp t fluids abstract experiments in a piston cylinder apparatus equilibrated natural fluorapatite with aqueous hcl nacl naoh na 2 co 3 and co 2 h 2 o mixtures at 1 2 0 gpa and 950 1050 c post experiment apatite compositions were determined by electron microprobe and fluid compositions were calculated from mass balance this enabled calibration of the fluorine and chlorine contents of apatite coexisting with a variety of fluids at high p and t and provides better constraints on the halogen composition of aqueous fluids which may exist in the deep crust and upper mantle results obtained at 2 0 gpa and 1050 c indicate that the ratio x clap x ohap in apatite x fap x clap and x ohap are the mole fractions of fluor chlor and hydroxyapatite is proportional to the chlorine content of the fluid up to 1 h 2 o co 2 5 h 2 o hcl and 15 h 2 o nacl wt cl in contrast the ratio x fap x ohap was found to vary in proportion to the fluorine content of the fluid only at concentrations of 0 15 h 2 o hcl and 0 4 h 2 o nacl wt f arising from changes in the activities of aqueous hcl and hf the results of this study demonstrate that fluid composition in addition to the absolute abundances of f and cl in the fluid will determine the amounts of these elements incorporated into coexisting apatite specifically relatively low cl and f concentrations in acidic h 2 o hcl fluids are required to obtain high ratios of x clap x ohap and x fap x ohap in apatite whereas much higher abundances of cl and f in basic fluids i e na bearing are required to achieve the same result in addition resulting from dilution of the aqueous phase with co 2 and the subsequent reduction in the activity of h 2 o apatites with high ratios of x clap x ohap and x fap x ohap may be produced by co 2 h 2 o fluids with relatively low levels of cl or f application of these results to apatites from a suite of ultramafic xenoliths from southeastern australia indicates chlorine abundances of 500 3500 ppm in the fluid phase and points to chlorine as a potentially important component of some mantle fluids

apatite compositions and groundmass mineralogy record divergent melt fluid evolution trajectories in coherent kimberlites caused by differing emplacement mechanisms kimberlites are pipe like igneous bodies consisting of a pyroclastic crater and diatreme commonly underlain by coherent root zone rocks and with associated dyke sill complexes the processes that control the different modes of coherent kimberlite emplacement remain uncertain in addition late evolution of kimberlite melts during emplacement into the upper crust remains poorly constrained therefore it is unclear whether there is a link between melt composition evolution and the emplacement mechanism of coherent kimberlites i e planar dykes sills vs irregular bodies in the root zone an absence of comparative studies on late stage magmatic phases across the different emplacement modes of coherent kimberlite from the same locality hamper resolution of these issues therefore we report petrographic and mineral chemical data for groundmass apatite in samples of dyke sill and root zone kimberlites from the kimberley cluster south africa early crystallised phases olivine spinel mg ilmenite in dyke sill and root zone kimberlites have indistinguishable compositions and hence crystallised from similar primitive melts conversely apatite compositions are generally distinct in dyke sill low sr high and variable si and root zone kimberlites high and variable sr low si the si enrichment of apatite in dykes sills is attributed to the coupled incorporation of co32 and sio44 for po43 reflecting higher co2 contents in their parental melts and potentially higher si contents due to the preferential crystallisation of carbonates over mica monticellite the low sr contents of apatite in dyke sill kimberlites reflect equilibrium with a kimberlite melt i e dsr is close to unity for carbonate and silicate melts whereas the higher sr contents of apatite in root zone kimberlites require crystallisation from or overprinting by a h2o co2 fluid significantly higher dsr the relative enrichment of co2 in kimberlite dykes sills is evident from the abundance of carbonates the presence of mesostasis dolomite and calcite phenocrysts in some samples and concomitant reduced proportions of other groundmass phases e g serpentine mica monticellite during late alteration of kimberlite dykes sills monticellite is typically replaced by carbonates whereas olivine and pleonaste are relatively stable indicating the melts which form dykes sills evolve to higher co2 h2o ratios it is unlikely that these two distinct evolutionary paths were caused by crustal contamination before or during near surface magma emplacement because crustal assimilation is not recorded in the o and sr isotopic composition of late crystallising olivine rinds or carbonates respectively we suggest that higher concentrations of co2 are retained in kimberlite dykes sills due to higher confining pressures i e lack of breakthrough to the surface in contrast exsolution of co2 from root zone kimberlites increased melt h2o co2 ratios and promoted the crystallisation of mica and monticellite at the expense of dolomite and calcite apatite compositions have the potential to aid in the discrimination of kimberlites from lamproites higher lree sr f and s lower si contents and carbonatites higher lree f cl and s lower fe contents however the compositions of kimberlitic apatite overlap those from aillikites probably due to similar late stage melt compositions

neodymium and strontium isotope content of microdiorite enclaves points to mantle input to granitoid production microdiorite enclaves are arguably the most poorly understood of the more prominent features of granitoids surprisingly they have been invoked as support for completely different models for the origin of chemical zonation in granitoids depending on whether they are interpreted as restites syn plutonic blobs of magma remobilized cumulate or basified country rock xenoliths here we present the first detailed neodymium and strontium isotope study of suites of such enclaves from two plutons in both cases we find relatively high nd values most readily explained if enclaves represent syn plutonic injections of mafic magma into the host granitoid magma as such they are the tangible remains of a very important process of mantle derived heat and mass transfer operating in the generation of granitic magmas

precambrian olistoliths masquerading as sills from death valley california olistolith production and magmatism are processes commonly associated with extensional tectonic settings such as rift basins we present a cautionary exemplar from one such precambrian basin in which we reinterpret metabasite bodies previously documented as sills to be olistoliths we nevertheless demonstrate that on the basis of field observation alone the previous but erroneous sill interpretation is parsimonious indeed it is only by using isotopic age and compositional analysis that the true identities of these metabasite olistoliths are revealed we present new data from metabasites and metasedimentary strata of the kingston peak formation cryogenian and crystal spring formation mesoproterozoic of death valley usa these include field observations u pb apatite ages u pb zircon ages detrital and igneous and whole rock geochemistry these data also provide a new maximum age for the base of the pahrump group and suggest that the crystal spring diabase was more tholeiitic than previously thought similar sill olistolith misinterpretations may have occurred elsewhere potentially producing erroneous age and tectonic setting interpretations of surrounding strata this is particularly relevant in precambrian rocks where fossil age constraints are rare this is illustrated herein using a potential example from the neoproterozoic literature of the lufilian belt africa we caution others against precambrian olistoliths masquerading as sills supplementary material details of a meta igneous boulder from p12 of the silurian hills la icp ms and whole rock geochemistry methods and standards and u pb apatite and zircon isotopic data including standards and selected cathodoluminescence images are available at https doi org 10 6084 m9 figshare c 3990639

evaporitic source model for igneous related fe oxide ree cu au u mineralization we propose that many igneous related fe oxide rich ree cu au u bearing deposits form by hydrothermal processes involving evaporitic ligand sources either coeval salars or older evaporites these deposits are abundant in both phanerozoic and proterozoic extensional continental and continent margin settings they commonly form in global arid zones but they also occur where magmatism is superimposed upon older evaporites magmatic compositions exert only second order control mainly on alteration mineralogy and on element abundances hot s poor brines generated by interaction with evaporitic materials are consistent with geologic settings and help rationalize the distinctive element enrichments siderophile lithophile and hydrothermal alteration sodic locally alkaline found in these systems this model contrasts with immiscible oxide melt and magmatic hydrothermal origins commonly proposed for these deposits although all three mechanisms can occur 31 refs 3 figs 1 tab

in situ major and trace element compositions of apatites from luanchuan orecluster implications for porphyry mo mineralization abstract the effects of volatile concentrations and oxidation state of magma on the mo mineralization potential have been explored through petrographic studies and in situ electron probe micro analyzer epma and laser ablation inductively coupled plasma mass spectrometry la icp ms of apatites from coeval economically mo mineralized granite porphyry and quartz diorite and sub economically mineralized granite porphyry at luanchuan orecluster the occurrence of abundant k feldspar xenocrysts possibly entrained from granitic magma in quartz diorite implying a magma mingling process studied apatites are fluorapatites or fluor hydroxyapatites with decreasing oh concentrations from economically mineralized quartz diorite 0 30 0 49 apfu through mineralized granite porphyry 0 14 0 41 apfu to sub economically mineralized granite porphyry 0 01 0 11 apfu chondrite normalized ree patterns of all the apatites are characterized by lree enrichment relative to mree and hree and negative eu anomaly similar to their host magmas indicating a melt composition control strontium concentration of studied apatites are probably controlled by the crystallization of plagioclase or alkali feldspar mineralized quartz diorite formed at a relatively reduced environment compared to other rocks but mineralized granite porphyry and sub economically mineralized granite porphyry formed at a similar oxidation state based on the so3 eu ce and mn content variation of apatites the oh contents of apatites combined with published log h2o hf ratios of melt in equilibrated with biotites reflect that economically mineralized intrusions have higher water contents than the sub economically mineralized intrusions in a porphyry mo system a high magma water content is probably a key parameter controlling mo mineralization mafic magma may supply water and heat to ore forming granitic magmas enhancing their mo mineralization potential

the role of apatite in mantle enrichment processes and in the petrogenesis of some alkali basalt suites analyses of sr and ree in apatites from a variety of mantle derived parageneses are used in conjunction with trace element data from the literature to investigate relationships between alkali basalts and apatite rich materials in upper mantle source regions despite difficulties in interpretation positive p anomalies in the hygromagmatophile element abundance patterns of some continental primary alkali basalts suggest either p enrichment of their source or assimilation of p rich material or both amphibole and apatite rich xenoliths occur in several alkali basalt provinces and by virtue of the p and lree enrichment represent a probable source of the p anomalies and part of the other trace element enrichments of these magmas incorporation of such apatite rich materials by later primary magmas would be enhanced by the high p2o5 concentrations required to achieve apatite saturation in basaltic liquids in the early stages of mantle diapirism an undersaturated magma produced by slight partial melting of garnet peridotite might fractionate as it rises to the range of amphibole stability hygromagmatophile element patterns of clinopyroxenite xenoliths indicate that clinopyroxene fractionation could produce p enriched liquids which might subsequently crystallize amphibole and apatite rich materials now represented by xenoliths during generation of later primary magma apatite rich materials might preferentially contaminate the liquids to yield positive p anomalies this model requires that magmas undergo prolonged fractionation at considerable depth 100 km a process which is apparently most probable in subcontinental environments an apatite and zircon bearing mica clinopyroxenite xenolith from matsoku provides a link between the s african marid suite and amphibole and apatite rich xenoliths from various alkali basalt provinces unusual ree patterns lan cen ndn cen yn 10 of apatites in this xenolith suggest a link between the marid suite xenoliths and postulated pre karroo mantle metasomatism

variation in the composition of apatite through the merensky cyclic unit in the western bushveld complex microprobe analysis of interstitial apatite from a 100 m section through the merensky reef of the bushveld complex reveals that this stratigraphic section marks a transition from cl rich to more f rich compositions in the critical and main zones respectively apatite compositions across the section vary by more than 80 mole percent in the chlorapatite component the trend of decreasing cl concentration with stratigraphic height is not regular and cl contents in apatites from some samples may vary as much as 50 mole percent la 2 o 3 and ce 2 o 3 tend to be enriched in the more melanocratic orthocumulate parts of the section sro concentrations of apatite show an increase with stratigraphic position a trend which is opposite that observed in coexisting cumulus plagioclase the data are consistent with mineralogic and textural evidence for an influx of cl rich vapor into the cumulus section which has affected the cl f variations through the lower portion of the bastard unit this influx occurred above the crystallization temperature of apatite 1 000 degrees 1 050 degrees c it is suggested that much of the modal variation seen in the section may be the result of shifts in liquidus field boundaries caused by gain or loss of volatile components from the melt

understanding the origin and evolution of water in the moon through lunar sample studies a paradigm shift has recently occurred in our knowledge and understanding of water in the lunar interior this has transpired principally through continued analysis of returned lunar samples using modern analytical instrumentation while these recent studies have undoubtedly measured indigenous water in lunar samples they have also highlighted our current limitations and some future challenges that need to be overcome in order to fully understand the origin distribution and evolution of water in the lunar interior another exciting recent development in the field of lunar science has been the unambiguous detection of water or water ice on the surface of the moon through instruments flown on a number of orbiting spacecraft missions considered together sample based studies and those from orbit strongly suggest that the moon is not an anhydrous planetary body as previously believed new observations and measurements support the possibility of a wet lunar interior and the presence of distinct reservoirs of water on the lunar surface furthermore an approach combining measurements of water abundance in lunar samples and its hydrogen isotopic composition has proved to be of vital importance to fingerprint and elucidate processes and source s involved in giving rise to the lunar water inventory a number of sources are likely to have contributed to the water inventory of the moon ranging from primordial water to meteorite derived water ice through to the water formed during the reaction of solar wind hydrogen with the lunar soil perhaps two of the most striking findings from these recent studies are the revelation that at least some portions of the lunar interior are as water rich as some mid ocean ridge basalt source regions on earth and that the water in the earth and the moon probably share a common origin

genesis of a low grade apatite ilmenite magnetite deposit in the kauhajarvi gabbro western finland the paleoproterozoic kauhajarvi gabbro is one of several fe ti and p rich mafic intrusions associated with granitoids in the fennoscandian shield in western finland the gabbro is cut by the late orogenic lauhanvuori granite ca 1870 ma whereas the surrounding area is composed of synorogenic collision related granitoids and calc alkaline volcanic rocks ca 1890 ma belonging to the mid finland granitoid complex the mafic intrusions were probably emplaced into a svecofennian rift zone they are characterized by a high phosphorus content the common occurrence of ilmenite as separate grains and the coeval crystallization of apatite fe ti oxides and fe mg silicates the kauhajarvi gabbro is composed of two geochemically and structurally distinct zones the basal zone is composed of poorly layered fine to medium grained gabbro which represents an early intrusion of tholeiitic magma and has rather high concentrations of chromium magnesium and silica typically the concentrations of iron titanium and phosphorus are low except for the top that is enriched in apatite and ilmenite during most of the crystal liquid fractionation of the basal zone magma low f o2 limited the crystallization of fe ti oxides instead titanium became enriched in the uppermost layer of the basal zone the main zone represents a later injection of more evolved tholeiitic magma and makes up 80 to 90 of the total intrusion volume peridotite is common along with gabbro and gabbronorite in the lower and middle parts of the main zone and anorthosite is common near the top of the main zone the mg fe ratio in mafic minerals and vanadium concentrations in magnetite decrease upwards the variation within the main zone can be explained by crystal liquid fractionation of a single batch of a parental magma under conditions of relatively high f o2 titanium is not progressively enriched the ratio of titanium to iron tio2 fe2o3 0 16 to 0 20 fe total as fe2o3 is constant in the main zone and normal for mafic intrusions titanium is sited in separate ilmenite grains and in lamella within ilmenomagnetite ti bearing magnetite the high phosphorus content in the main zone is interpreted to result in crystallization of ilmenite and ilmenomagnetite instead of ti rich magnetite under relatively high f o2 conditions high concentrations of titanium iron and phosphorus in rocks of the main zone can be explained by pre emplacement crystal melt fractionation in a deep magma reservoir and or contamination of mantle derived mafic magmas by granitic magmas from partial melting of crustal rocks a low grade fe ti p resource at kauhajarvi consists of layers with as much as 20 wt combined ilmenite usually 8 to 11 wt apatite 1 to 8 wt and magnetite 1 to 9 wt mineralized layers are of variable thickness 2 m to 30 m and occur in variable host rocks peridotite or gabbro the fe ti oxides are most abundant in peridotite and pyroxene or olivine rich gabbronorite within the main zone the contact between mineralized rocks 4 tio2 and non or slightly mineralized rocks is gradual the deposit as a whole consists of three to five mineralized layers with maximum combined thickness of 70 m apatite is most abundant in the oxide rich layers but is locally also concentrated in anorthosite with low fe ti oxide contents the weight ratio of ilmenite to magnetite is 3 2 the ratio of total ti fe oxides to apatite averages 4 0 with the range of 1 5 to 15

sulfur evolution of oxidized arc magmas as recorded in apatite from a porphyry copper batholith uniformly sulfur rich cores abruptly zoned to sulfur poor rims 1 to 0 2 wt so3 in apatite from the yerington batholith nevada indicate that early magma that is crystal poor oxidizing and sulfate rich evolved to sulfate poor magma via crystallization of anhydrite a mineral observed in magmas from pinatubo and el chichon we predict that the characteristic zonation to sulfur poor rims of apatite in the yerington batholith is common in other oxidized hydrous calc alkaline magmas and can be used to track cryptic anhydrite saturation as well as to monitor sulfur evolution sulfate rich arc magmas such as yerington magmas may crystallize to produce hydrothermal fluids rich in chlorine copper and sulfur and porphyry copper ores

lead diffusion in apatite and zircon using ion implantation and rutherford backscattering techniques abstract ion implantation was used to introduce pb into the minerals zircon and apatite diffusion profiles were obtained using rutherford backscattering and the results were fitted with a model to determine the diffusion coefficients this approach is both simple and useful in studying diffusion over a temperature range of geologic interest without inordinate annealing times results for apatite over the temperature range 600 900 c are in good agreement with earlier results obtained for higher temperatures watson et al 1985 and are described by the following arrhenius law d 1 27 10 4 cm 2 s 1 exp 54 6 1 7 kcl mol 1 rt this suggests that radiation damage induced by ion implantation has little effect on pb diffusion in this case due to rapid annealing of induced damage at low temperatures the activation energy stated above is somewhat smaller than that previously determined 70 kcal mol 1 reflecting the larger range in 1 t sampled by the present results closure temperatures calculated with these diffusion parameters are in good agreement with those inferred from geochronologic data diffusion coefficients for pb in zircon determined in this study are greater than those obtained from a single experimental measurement and estimates of pb diffusion based on geochronologic data and u pb zoning in natural zircons the differing results for zircon and apatite obtained in this study appear to be related to each mineral s ability to anneal the radiation damage induced by ion implantation

local equilibrium of mafic enclaves and granitoids of the turtle pluton southeast california mineral chemical and isotopic evidence free to read on publisher s website major element and trace element compositions of whole rocks mineral compositions and rb sr isotopic compositions of enclaveand host granitoid pairs from the early cretaceous calc alkalineturtle pluton of southeasterncalifornia suggest that the local environment profoundly affects some enclave types in the turtle pluton where the source of fine grained mafic enclaves can be deduced to be magmatic by the presence of partially disaggregated basaltic dikes mineral chemistry suggests partial or complete local equilibrium among mineral species in the enclaveand its host granitoid because of local rb sr isotopic equilibration betweenfine grained enclaves and host granitoid one cannot use sr isotopes to distinguish an enclave source independent of its host rocks from an enclave sourcerelated to the enclosing pluton however preliminary nd isotopic data suggestan independent mantle source for enclaves

subduction related petrogenesis of late archean calc alkaline lamprophyres in the yilgarn craton western australia abstract we present a comprehensive petrographic mineralogical and geochemical study of calc alkaline lamprophyres cal from the archean yilgarn craton western australia previous studies have shown that the emplacement age of cal from the eastern goldfields superterrane of the yilgarn craton is 2684 to 2640 ma a new rb sr mica age for a cal sample in the western yilgarn is 2070 ma both archean and proterozoic cal analysed in this study display porphyritic textures and contain phenocrysts of amphibole minor clinopyroxene and biotite in a fine grained groundmass dominated by feldspar high mgo ni and cr abundances up to 11 9 wt 373 and 993 ppm respectively are consistent with derivation of primitive magmas from a mantle source enrichment in h2o reflected in the abundance of magmatic amphibole and mica combined with high whole rock lile th yb ratios and negative nb ta anomalies in trace element patterns are consistent with a source that was metasomatised by hydrous fluids analogous to those generated by phanerozoic subduction related processes chondritic nd and hf signatures and archean mantle like sr isotope signatures of the late archean cal indicate that the fluid metasomatism required to explain their volatile and trace element enriched composition shortly preceded partial melting i e there was insufficient time to develop enriched radiogenic isotopic signatures the concurrence of apparently juvenile radiogenic isotopes and fluid related trace element compositions requires a geodynamic scenario whereby dehydration of a subducted slab triggered metasomatism of the overlying mantle wedge our findings therefore support a subduction setting at 2 6 2 7 ga along the eastern margin of the yilgarn craton the cal from the western yilgarn have similar compositions but enriched sr nd hf isotopes compared to those in the eastern goldfields superterrane this signature is consistent with melting of lithospheric mantle domains previously enriched by subduction related metasomatism hence our study suggests the presence of a subduction setting in the western yilgarn during the archean which is consistent with previous geodynamic reconstructions however the geodynamic trigger for the early proterozoic event that generated cal magmatism in the western yilgarn is currently unclear

an evaluation of models of apatite compositional variability using apatite from the middle banded series of the stillwater complex montana apatite is a relatively common accessory mineral in the olivine bearing zones ob iii and ob iv of the middle banded series of the stillwater complex occurring interstitial to cumulus grains as monomineralic inclusions in cumulus grains and in polymineralic clusters which may or may not be included in the cumulus grains eighty nine of 185 samples examined were found to contain some apatite the f cl oh content of the apatite show distinct stratigraphic variations xclap mole fraction cl in apatite of interstitial apatite increases upsection in both ob iii and ob iv with average values ranging from 0 15 to 0 85 in ob iii and from 0 03 to 0 60 in ob iv xfap varies inversely with xclapwith average values ranging from 0 00 to 0 70 while xohap remains relatively constant near 0 40 or decreases slightly with height these variations are remarkable given that no appreciable stratigraphic variations in either the major or trace element compositions of any of the cumulus minerals are found in the 800 m of section that comprise ob iii and ob iv within sample variation of xclap for samples containing cl rich apatite is substantially larger up to 0 65 xclap than for samples with more f rich apatite xclap varies by approximately 0 15 although interstitial apatite is found throughout ob iii and ob iv apatite occurring as monomineralic inclusion in cumulus grains or in polymineralic clusters is almost exclusively found in samples with cl rich apatite the data are best explained by a model involving the degassing of a cl rich volatile phase from the crystallizing interstitial liquid the up section migration of this fluid resulted in the crystallization of f rich apatite in the lower portion and progressive cl enrichment in the apatite with height the presence of hornblende bearing dikes veins and pegmatoids at the level of maximum cl enrichment is consistent with a fluid migration model

ore forming potential of alkaline magmas abstract geochemical models of the genesis of the largest rare metal deposits connected with agpaitic nepheline syenites are discussed in this paper thermodynamic calculations demonstrate that high alkalinity prevents the separation of volatile components into the gas phase the rare earth deposits have been formed at the magmatic stage during the process of crystal differentiation jointly with convection in the magmatic system the saturation of alkaline magma in respect of ore minerals at early stages of crystallization is considered to be the necessary condition for the formation of cumulative magmatic deposits these considerations are proved by data on micro inclusions

spatial and temporal trends in exhumation of the eastern himalaya and syntaxis as determined from a multitechnique detrital thermochronological study of the bengal fan the bengal fan provides a neogene record of eastern and central himalaya exhumation we provide the first detrital thermochronological study apatite and rutile u pb mica ar ar zircon fission track of sediment samples collected during international ocean discovery program iodp expedition 354 to the mid bengal fan our data from rutile and zircon fission track thermochronometry show a shift in lag times over the interval 5 59 3 47 ma the oldest sample with a lag time of 6 m y has a depositional age of 5 59 4 50 ma and the zircon and rutile populations then show a static peak until 12 ma this interval from 5 59 4 50 ma to 12 ma is most easily interpreted as recording passive erosion of the greater himalaya however single grains with lag times of 4 m y but with high analytical uncertainty are recorded over this interval for sediments older than 10 ma these grains were derived from the greater himalaya which was exhuming rapidly until ca 14 ma in sediments younger than 10 ma these grains could represent slower yet still rapid exhumation of the syntaxial antiform to the south of the massif lag times 1 m y are again recorded from 14 5 ma to the base of the studied section at 17 ma reflecting a period of greater himalayan rapid exhumation mica 40ar 39ar and apatite u pb data are not sensitive to syntaxial exhumation we ascribe this to the paucity of white mica in syntaxial lithologies and to high levels of common pb resulting in u pb ages associated with unacceptably high uncertainties respectively

apatite in igneous systems apatite is a minor but ubiquitous mineral in most igneous rocks although the modal proportion of apatite in common rocks is generally low it can reach high concentrations in enclaves cumulates and other rocks of low abundance i e rocks that constitute a small volume of the crust and mantle e g nelsonites the presence of apatite in most rocks is due not only to its low solubility in naturally occurring melts and aqueous solutions but also to the limited ability of common rock forming minerals to accept the amount of phosphorus that occurs in most rocks into their structure in this paper we will discuss some aspects of the occurrence texture composition physical chemistry and petrogenetic significance of apatite in felsic rocks i e andesite to rhyolite and their plutonic analogs in mafic i e basalts and related rocks and plutonic analogs and ultramafic rocks of the earth s crust and mantle fluorapatite is by far the most common member of apatite family found in igneous rocks however most natural fluorapatite contains some chlorine and hydroxyl as well and these constituents can attain high concentrations in some cases the other halogens bromine and iodine also occur in apatite but their concentrations are much lower than chlorine and fluorine many cations commonly substitute for calcium and phosphorus in apatite however they rarely reach concentrations that warrant the definition of a separate mineral species apatite can be described by the general formula a5 xo4 3z following sommerauer and katz lehnert 1985 the a site accommodates large cations e g ca2 sr2 pb2 ba2 mg2 mn2 fe2 ree3 eu2 cd2 na pan and fleet ch 2 in this volume and comprises two sites that exhibit vii fold

petrography and mineral chemistry of the composite deboullie pluton northern maine u s a implications for the genesis of cumo mineralization abstract biotite and apatite mineral chemistry particularly halogen abundances and ratios are used to investigate the relation of the two contrasting parts of the deboullie composite pluton syenite granodiorite located in northern maine biotite mineral chemistry helps to classify the weakly developed porphyry style mineralization cu mo associated with syenitic rocks of the deboullie pluton unmineralized syenite consists of k feldspar plagioclase quartz biotite hornblende clinopyroxene and minor amounts of apatite titanite magnetite zircon and allanite biotite and apatite occur within the matrix of the rocks and within small multiphase inclusions hosted by clinopyroxene the inclusions are interpreted to be crystallized melt inclusions rather than solid inclusions that were trapped by clinopyroxene during growth the multiphase inclusions consist of k feldspar quartz biotite apatite magnetite the f contents of biotite display a strong positive correlation with the phlogopite component or xphl xphl mg sum octahedral cations biotites from the multiphase inclusions have higher f contents and higher values of f f cl oh and xphl than biotites in the matrix that presumably formed later during crystallization and or re equilibrated with late stage fluids contents of tio2 largely overlap for the inclusion and matrix biotite apatite compositions plot within the fluorapatite field f f cl oh 0 57 0 99 apatites in the multiphase inclusions have higher cl contents than apatites in the matrix or those enclosed in biotite biotite apatite geothermometry for the multiphase inclusions yields magmatic or near magmatic temperatures 725 850 c biotite apatite pairs outside the inclusions yield temperatures that range from near magmatic 600 775 c to much lower x f x cl and xphl was used to infer hf hcl fugacity ratios in associated hydrothermal fluids and indicates that biotite from the deboullie pluton is strikingly similar to biotite from the porphyry cu deposit at santa rita new mexico but distinctly different from biotite from the porphyry mo deposit at henderson colorado the assemblage quartz magnetite titanite implies an oxidation state for the deboullie pluton well above the quartz magnetite fayalite buffer which is also consistent with magmas associated with porphyry cu deposits on a regional scale biotite compositions from granitic plutons in maine do not vary in a systematic manner this implies that biotite compositions no longer directly reflect source compositions finally biotite and apatite compositions of the syenite and granodiorite are different compositional ranges in the granodiorite are more restricted than those in the syenite this provides evidence that the two parts of this composite pluton had different origins and are not related by crystal fractionation

petrology of the yerington batholith nevada evidence for evolution of porphyry copper ore fluids the jurassic yerington batholith western nevada is a composite pluton that contains several centers of porphyry copper mineralization and is exposed in structural cross section at paleodepths ranging from 0 to 8 km within these exposures the mcleod hill quartz monzodiorite bear quartz monzonite and luhr hill granite form successive intrusions that are in turn volumetrically smaller approximately 75 19 and 6 vol respectively more deeply emplaced tops at 65 km 3 luhr hill granite the low cu content approximately 10 ppm of the granite would allow extraction of approximately 50 ppm cu from it during crystallization these data suggest an orthomagmatic model in which both high and low density saline aqueous fluids formed during exsolution of water from the crystallizing luhr hill granite and from which salts cu fe and s strongly partitioned into the high density ore fluid low density fluids may have risen from the magma as a vapor plume mineralization occurred when fluid overpressures caused fracturing of wall rock and upward intrusion of granite porphyry dikes and high density saline ore fluids both the f sub o 2 path during subsolidus cooling and the deposition of most s as chalcopyrite pyrite in ore suggest that reduction of magmatic s to sulfide may have been a mechanism for oxidation of magmatic ferromagnesian silicate and fe ti oxide minerals