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

late wenlock sequence and bentonite stratigraphy in the malvern suckley and abberley hills england abstract the late wenlock series homerian stage of the central midland platform occupies an area stretching from ledbury to the malvern suckley and abberley hills based upon the establishment of a sequence stratigraphic framework for the much wenlock limestone formation and the immediately under and over lying coalbrookdale and lower elton formations comparisons can now be made with key sections across the northern midland platform and beyond these correlations have been strengthened by the determination of apatite rare earth element ree geochemical signatures obtained from four volcanic ash layers bentonites at whitman s hill quarry herefordshire which allow for comparisons with published coeval sections at wren s nest hill west midlands and wenlock edge shropshire as well as with bentonites described from the island of gotland sweden across the study area fifteen parasequences associated with two pronounced regressive episodes separated by a marked transgression can be identified the lithological responses to these relative sea level changes are the same as those reported from the west midlands including the threefold division of the much wenlock limestone formation into lower quarried limestone nodular beds and upper quarried limestone members apatite ree geochemical signatures from whitman s hill quarry identify three bentonites which probably originated from a granodiorite magmatic source while a fourth bentonite has a distinctively mafic composition more akin to that of a gabbro or syenite this distinctively mafic bentonite is preserved on a marked flooding surface within the nodular beds member and appears compositionally and stratigraphically equivalent to a bentonite at wren s nest hill west midlands furthermore in both sections this bentonite is of notable thickness 120 200 mm allowing for its identification in other sections across the region comparisons with gotland identify three closely spaced bentonites of a similar mafic composition to the bentonite described from the midland platform while similarities in stratigraphic position and composition do not at present allow for the identification of a single ash fall event covering both the midland platform and gotland they are indicative of a shared source region which may offer the possibility for future bentonite correlation between these regions

magmatic graphite inclusions in mn fe rich fluorapatite of perphosphorus granites the belvis pluton variscan iberian belt three mn fe rich fluorapatite types have been found in the highly evolved peraluminous and perphosphorous granites of the belvis pluton one of these apatite types includes abundant graphite microinclusions suggestive of a magmatic origin for the graphite the belvis pluton is a reversely zoned massif composed by four highly fractionated granite units showing a varied accessory phosphate phases u rich monazite u rich xenotime u rich fluorapatite and late eosphorite childrenite the strong peraluminous character of the granites determines an earlier monazite and xenotime crystallization so the three types of fluorapatite record late stages of phosphate crystallization the earlier type 1 apatite is mostly euhedral small and clear type 2 apatite is dusty large 2800 m and mostly anhedral with strong interlobates interfaces with the main granite minerals more abundant in the less fractionated units and absent in the most evolved unit type 3 is subeuhedral to anhedral shows feathery aggregate texture and only appears in the most evolved unit apatite composition was acquired by electron microprobe analyses laser ablation inductively coupled plasma mass spectrometry and electron energy loss spectroscopy type 1 and type 2 apatite display similar broad compositional ranges showing high mno up to 4 30 wt and feo up to 2 88 wt contents without traces of carbon in apatite structure type 2 differs from type 1 by having slightly higher lree and sr contents ree spectra also differ with type 1 displaying both variable lree slope and negative eu anomaly whereas type 2 shows constant lree slope and higher negative eu anomaly although both display similar hree slope type 3 apatite displays higher feo contents up to 5 09 wt positively correlated with higher cl na li be b zn contents and extremely low y ree contents when compared to the other apatite types cation substitution indicates that part of the fe content is as fe graphite has been found exclusively as abundant microinclusions in type 2 apatite parallel or randomly distributed and heterogeneously grouped in clusters within the crystals high resolution electronic images show that graphite occurs with unusual habits filaments of stacked hexagonal flakes up to 15 m length and up to 0 5 m width textural and chemical features suggest a highly crystallized melt which favor compartmentalizing in compositional microdomains where the apatite types would have crystallized the cocrystallization of type 2 apatite and graphite suggests a c f p rich melt sufficiently saturated to acquire an immiscible character with the highly evolved silicate melt in late magmatic stages as type 2 differs from type 1 apatite by higher lree and sr contents we interpret that fluxing components were favorably concentrated in those residual less depleted lree sr fraction melts once monazite and zircon and xenotime would have crystallized type 3 apatite records a change in the ultimate melt stage an increase of the oxygen fugacity coupled with high undercooling by volatile lost of highly fractionated residual cl richer melts the presence of biogenic carbon in granite peraluminous melts derived from metasedimentary sources and its later crystallization as graphite filaments opens a discussion on the carbon behavior during magma evolution especially in highly polymerized melt framework

cathodoluminescence of synthetic doped with rare earth elements and natural anhydrites abstract in order to interpret cathodoluminescence cl spectra of natural anhydrites synthetic crystals were indirectly obtained by precipitation of gypsum from solutions containing doping rare earth elements ree and by transformation into anhydrite by dehydration at 800 c during 3 h analyses by icp ms of several anhydrites obtained from solutions containing 130 ppm of ree clearly showed that light ree lree can be concentrated to up to 2000 3000 ppm in the solid heavy ree hree are less prone to enter the structure and only 255 ppm were found for lu ree such as ce3 pr3 sm3 eu2 gd3 tb3 dy3 and tm3 display strong cl emissions and spectra usually are complex except for three of them with intense emissions in the near uv domain ce3 306 327 nm gd3 314 nm and eu2 386 nm in the near ir domain only nd3 874 nm gives an important luminescence several natural anhydrites were examined for ree cl emissions a sample from the faraday uranium mine bancroft ontario presents mainly a strong ce3 emission with traces of eu2 dy3 sm3 and nd3 in the anhydrite from balazuc france gd3 eu2 and dy3 are the more abundant followed by ce3 and traces of tb3 and sm3 a crystal probably from hall tyrol displays gd3 ce3 er3 tb3 dy3 and sm3 its analysis by icp ms showed that the cl can be induced by only some ppm of these elements even less than 1 ppm for er3 and tb3

apatite fission track analysis apatite fission track aft analysis has been widely used during the past 30 years to constrain the low temperature thermal histories of many igneous metamorphic and sedimentary rocks in a wide range of geological settings applicable geological settings include orogenic belts rifted margins faults sedimentary basins cratons and mineral deposits the types of geologic problems that can be addressed include the timing and rates of tectonic events sedimentary basin evolution the timing of hydrocarbon generation and ore mineralization the absolute age of volcanic deposits the effects of major climatic changes on the near surface geothermal gradient and long term landscape evolution early work by naeser 1967 and wagner 1968 1969 first established the basic procedures that enabled the fission track dating method to be applied routinely to these geologic problems fleischer et al 1975 summarized the early studies of the broader discipline of nuclear track detection in different solid state materials more recent comprehensive overviews of fission track applications have been provided by naeser and mcculloh 1989 wagner and van den haute 1992 gallagher et al 1998 van den haute and de corte 1998 dumitru 2000 and gleadow et al 2002 etched natural fission tracks in several apatite grains are shown in figure 1 successful aft analysis is limited by the following 1 the availability of apatite from which useful aft data can be obtained often due to a lack of apatite of sufficient grain size and quality within available rock types or alternatively the lack of available rock samples due to minimal outcrop exposure or other reasons 2 economic considerations in terms of the time and money required to obtain sufficient aft data 3 the inherent limitations of aft data to resolve geological thermal history information often related to limited numbers of accumulated spontaneous fission tracks due to

magmatic zoning in apatite a monitor of porosity and permeability change in granites apatites from the shap granite northern england are strongly zoned reflecting multiple generations of growth and dissolution such chemical zoning is most readily displayed in cathodoluminescence images and correlates well with trace element variation determined using la icp ms analyses the zoned apatites provide a detailed record of the changing scales of permeability during progressive crystallisation within the magma chamber early periods of apatite growth are preserved within cores and represent both early growth within a magma chamber dominated by vigorous mixing processes and inherited grains with significantly different chemistries the main phase of apatite growth within the magma was strongly controlled by the presence of adjacent biotite phenocrysts and is characterised by fine scale oscillatory zoning followed by the growth of a thin rim of relatively uniform composition the chemical evolution of the later phases of apatite growth and the stratigraphy of the zoning appear to record late stage crystallisation within progressively more isolated interstitial melt pockets

fission track dating of phosphate minerals and the thermochronology of apatite several phosphate minerals have been investigated for their usefulness in geochronology and thermochronology by the fission track method of these apatite ca5 po4 3 f cl oh has proved pre eminently suitable for this purpose for reasons discussed below apatite was one of the first minerals amongst many others to be investigated for fission track dating by fleischer and price 1964 and has subsequently become by far the most important of all the minerals used for dating by this method the usefulness of apatites for fission track dating arises from their near universal tendency to concentrate uranium within their structure at the time of crystallization and their widespread occurrence in all of the major rock groups price and walker 1963 first recognized the possibility that the accumulation of radiation damage tracks in natural minerals from the spontaneous nuclear fission of 238u within their lattices could be used for geological dating they also demonstrated that a simple chemical etching procedure served to enlarge these fission tracks to optical dimensions so that they could be observed and measured under an ordinary optical microscope price and walker 1962b 1963 this simple procedure quickly opened the way for a wide range of nuclear particle track studies in natural minerals and glasses e g fleischer et al 1975 the most important of which was fission track dating fleischer et al 1964 also showed that spontaneous or fossil fission tracks provided an explanation for various anomalous etch pits in apatite which had puzzled crystallographers over many years the essence of a fission track age determination involves measuring the number of tracks that have accumulated over the lifetime of the mineral along with an estimate of the amount of uranium that is present knowing the rate of spontaneous fission decay a geological age can be calculated detailed

a tephrochronologic method based on apatite trace element chemistry geochemical correlation of ash fall beds with conventional tephrochronologic methods is not feasible when original glass composition is altered thus alternative correlation methods may be required initial studies of heavily altered paleozoic tephra k bentonites have suggested the potential for employing trace element concentrations in apatite as ash fall bed discriminators to further test the utility of apatite trace element tephrochronology we analyzed apatite phenocrysts from unaltered volcanic rocks with an electron microprobe nine samples from rocks erupted during the quaternary and one sample from a rock erupted during the paleogene the resulting apatite trace element data provide unique bed discriminators despite within crystal variability each of the volcanic rocks studied possesses unique trends in mg cl mn fe ce and y concentrations in apatite the results from this study establish an important tephrochronologic method that can be applied to nearly all portions of the phanerozoic stratigraphic record and greatly assist development of an advanced timescale in addition to establishing a fingerprint for a particular eruption apatite chemistry provides useful information about the source magma

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

revealing hidden structures the application of cathodoluminescence and back scattered electron imaging to dating zircons from lower crustal xenoliths abstract the use of cathodoluminescence cl and or back scattered electron bse imaging techniques with in situ ion probe analyses of zircons can help unravel complex crustal histories of metamorphic rocks that otherwise might remain elusive using these techniques we have imaged zircons from three lower crustal xenolith suites that have previously been dated by shrimp sensitive high resolution ion microprobe in all three cases the zircons are featureless in transmitted light but cl and bse reveal internal structures that correlate with distinct growth events generally cl and bse images reveal similar structures with cl showing finer detail neither imaging technique is capable of delineating all growth features in every sample and the best results are obtained using a combination of the two techniques igneous cores in zircons commonly emit a different color cl emission in many cases zoning in the cores is truncated indicating that the zircons either spent time in the supracrustal environment after their initial crystallization and prior to the granulite facies event s or that part of the core zircon was resorbed during the subsequent metamorphic event metamorphic rims when present are commonly 10 to 30 m thick and are nearly always unzoned and featureless igneous cores and metamorphic overgrowths commonly have distinctive cl emission spectra and trace element concentrations however the cl spectra can only be used to qualify chemical differences as a linear relationship has not been shown to exist between cl intensity and trace element concentration in natural zircons in many cases the hf y p u and the heavy rare earth elements hrees concentrations can be correlated to igneous and metamorphic growth using a combination of cl and bse imaging techniques and in situ trace element analyses with either the electron microprobe or pixe particle induced x ray emission

autoradiography by x ray excited optical luminescence xeol application to scheelite and fluorite mineralisation this paper investigates the practical application of xeol as an autoradiography technique of use in characterising the mineralogy of geological samples a simple apparatus is described in which thin sections are excited with a low power x ray tube operated at 19 kv 0 9 ma luminescence is detected on photographic film 400 asa using a camera focused through a leaded glass window onto the rear of the thin section xeol autoradiographs recorded for exposure times varying from 3 to 120 min are presented for zinc sulphide powder a test sample scheelite in a wolframite bearing quartz vein and fluorite plus calcite in a fluorite calcite quartz vein the latter two samples being collected from mineralised localities in the eastern highlands of scotland u k these xeol autoradiographs show not only the distribution of the specified phases but also delineate textural information of value in interpreting mineralisation processes

analysis of atlantic sst variability factoring interbasin links and the secular trend clarified structure of the atlantic multidecadal oscillation abstract atlantic sst variability in the twentieth century is analyzed factoring the influence of natural sst variability in the pacific basin and the secular change in global ssts the tropical and northern extratropical basins are analyzed together using the extended eof technique which permits extraction of the interannual and multidecadal modes in the pan atlantic basin in a single step the leading mode of pacific uninfluenced sst variability is a multidecadal oscillation focused in the extratropical basin with a period of 70 yr the mode differs from the conventional atlantic multidecadal oscillation amo in the near quiescence of the tropical subtropical basin highlighting the significant influence of the pacific basin on this region in conventional analysis as much as 45 of the regional variance resulting from the conventional amo is due to this influence the second and third modes capture the growth east to west development and decay near simultaneous loss of amplitudes of interannual

new constraints on the timing of host rock emplacement hydrothermal alteration and iron oxide apatite mineralization in the kiruna district norrbotten sweden high spatial resolution zircon u pb geochronological data obtained directly on the kiirunavaara iron oxide apatite ioa deposit related orebodies and host rocks provide new constraints on the timing of mineralization in these deposits these data raise new arguments in the debate of a magmatic versus hydrothermal metasomatic genesis of these major 2 500 mt 30 70 wt fe paleoproterozoic deposits the main orebody at kiirunavaara contains ti poor magnetite and minor 0 05 5 wt p apatite located between a trachyandesite footwall and a rhyodacite hanging wall which also hosts smaller orebodies nukutus rektorn and tuolluvaara the pervasive na and k metasomatism in the host rock is documented by whole rock geochemical data and cathodoluminescence cl microscopy zircon u pb data for the metavolcanic rocks in the footwall and hanging wall cluster between 1884 4 and 1880 3 ma in the footwall a syenite aplite system yields ages of 1880 7 and 1881 4 ma a granite pluton exposed underground has an age of 1874 4 ma zircons in two ore samples never directly dated before this study yield ages of 1877 4 and 1874 7 ma brecciation at the contacts between the ore and host rocks the tight age at ca 1880 ma for most volcanic and plutonic rocks in the footwall and hanging wall and the marginally younger age for ore at ca 1877 to 74 ma matching the age of the spatially related granite pluton suggest a magmatic hydrothermal emplacement model for the kiruna area ioa ores

ecological and physiological variability of sr ca and ba ca in mammals of west european mid wurmian food webs the middle to upper paleolithic transition in western europe is characterized from an ecological point of view by large ungulate communities adapted to cold climatic conditions the aim of this study is to reconstruct the trophic relationships prevailing in these paleoecosystems which have no equivalent in the modern world bone and dentine remains representing five mammalian assemblages dated around 35 ka bp one of which included a neandertal specimen are investigated for sr ca and ba ca of bioapatites examination of the n content and u ree luminescence of bulk material ca p ratios and mn and ca contents of purified samples demonstrates that the sr ca and the ba ca ratios of bone and dentine samples are not significantly altered by diagenesis as a consequence of the biological discrimination of sr and ba in relation to ca sr ca and ba ca values are impoverished with increasing trophic position and are strongly correlated within a trophic web the slopes of the linear regressions between sr ca and ba ca are consistent with modern variability furthermore a statistical difference was found between ba ca of foregut and hindgut herbivores when coexisting collagen is preserved the sr ba ca and 15n are strongly correlated the distribution of values suggests that the 15n range is mainly controlled by the variability of soil conditions whereas the 13c range may be related to resource availability

north south extension in the tibetan crust triggered by granite emplacement we combine zircon sensitive high resolution ion microprobe u pb spot dating and mica 4 0 ar 3 9 ar plateau ages with field geological and geochemical constraints from the malashan area of southern tibet to show that the deformed granite core of the north himalayan metamorphic domes in this area is not indian basement but was intruded and deformed during the himalayan orogeny microstructural observations reveal that a transition from top to the south thrust related to top to the north extension related deformation occurred during granite intrusion and related metamorphism this suggests that intrusion triggered the onset of extensional tectonics in the tibetan middle to upper crust expected positive feedback mechanisms between decompression melting leading to more intrusion and more extensional deformation suggest that this mechanism may have been important on a regional scale

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

upper wenlock bentonites from wren s nest hill dudley comparisons with prominent bentonites along wenlock edge shropshire england the upper wenlock series homerian stage of the northern midland platform england contains numerous volcanic bentonite clay layers at wren9s nest hill dudley 15 bentonites have been investigated and comparisons with the type wenlock have been made by means of two key sections along wenlock edge shropshire in total 22 bentonites have been investigated and their clay and sand grade mineralogies determined rare earth element ree and yttrium concentrations of apatite grains contained within ten of the bentonites have been established allowing geochemical fingerprinting as an indication of provenance of source magmas and identification of geochemical marker beds based on the analysis of ree and yttrium concentrations it seems likely that the majority of these bentonites originated from a granodiorite magmatic source comparisons with published llandovery and lower wenlock age bentonites indicate generally more enrichment in light rees relative to heavy rees in addition close geochemical similarities between bentonites along wenlock edge and at wren9s nest hill strongly argue for their presence as precise stratigraphic equivalents within the upper much wenlock limestone formation these correlations are further supported by geophysical data from borehole wire line logs across the west midlands finally a chemically distinct mid homerian episode of volcanism is identified and represents a potentially important marker interval between the study area and other similarly aged bentonites reported from the island of gotland sweden

trace element partitioning between apatite and silicate melts we present new experimental apatite melt trace element partition coefficients for a large number of trace elements cs rb ba la ce pr sm gd lu y sr zr hf nb ta u pb and th the experiments were conducted at pressures of 1 0 gpa and temperatures of 1250 c the rare earth elements la ce pr sm gd and lu y and sr are compatible in apatite whereas the larger lithophile elements cs rb and ba are strongly incompatible other trace elements such as u th and pb have partition coefficients close to unity

lree redistribution among fluorapatite monazite and allanite at high pressures and temperatures the ree enrichment process in fluorapatite and the ree redistribution among fluorapatite monazite and allanite were studied in a series of three sets of experimental runs at p t conditions of 0 5 to 4 gpa and 650 to 900 c the first two sets of experimental runs utilized fluorapatite as a p source synthetic monazite or allanite as the ree sources albite quartz and naf h2o or nacl h2o the third set of runs was carried out with powdered ca3 po4 2 allanite quartz al2o3 and a naf h2o solution in all runs ree bearing fluorapatite with up to 28 wt ree2o3 formed at the expense of monazite or allanite either as narrow zones at the margin of synthetic fluorapatite in runs 1 and 2 or as discrete grains in run 3 the ree enrichment of fluorapatite in melt bearing runs is explained in terms of the high solubility of monazite in the presence of alkali rich melts together with the high partitioning values for rees among fluorapatite and alkali rich melts the formation of ree enriched fluorapatite in melt absent runs implies that the solubility of monazite and the ree uptake of fluorapatite are similarly high in both alkali rich melts and fluids and depends foremost on the activity of alkalis in fluids or melts the results from this study show the importance of fluorapatite as a ree carrier in rocks whose petrogenesis involved alkali bearing fluids melts in metamorphic rocks alkali enriched fluids or melts will likely form under higher grade conditions explaining the preferential occurrence of reeenriched fluorapatite in granulite and eclogite facies rocks

apatite in the ilimaussaq alkaline complex occurrence zonation and compositional variation abstract apatite from the augite syenite and the roof sequence of layered nepheline syenites pulaskite foyaite sodalite foyaite and naujaite of the ilimaussaq alkaline complex has been analysed by electron microprobe for ca p na si selected rare earth elements ree f and cl in the augite syenite chilled facies and middle zone euhedral apatite crystals are relatively abundant as inclusions in other liquidus phases the ree content is ca 1 wt ree 2 o 3 the same level is found in interstitial apatite in the coarse grained innermost facies ree enriched intercumulus apatite overgrowths are common and can have up to ca 18 wt ree 2 o 3 apatite is a common phase in the pulaskite and foyaite whereas it is rare in the sodalite foyaite and naujaite based on compositional variation and zoning it is possible to distinguish four generations of apatite in the layered roof sequence 1 primary apatite belonging to the high temperature mineral assemblage this apatite occurs in the pulaskite foyaite and sodalite foyaite as oscillatory zoned crystals whereas only remnants are found in the naujaite the ree enrichment is dominated by the ca 2 p 5 ree 3 si 4 substitution and maximum ree 2 o 3 exceeds 20 wt 2 irregularly zoned apatite occurs as rim zones on the primary apatite in the foyaite and as the dominant type of apatite in the sodalite foyaite and naujaite most irregularly zoned grains are altered primary apatite during the dissolution and recrystallisation process the composition gradually changed towards a lower ree content 3 overgrowths of homogeneous apatite on the irregularly zoned apatite in the naujaite 4 na and ree rich apatites occur in the foyaite sodalite foyaite and naujaite either as overgrowths on earlier generations of apatite or as individual crystals calculated chondrite normalised patterns show that the later generations of apatite are relatively enriched in lree and depleted in hree the most pronounced evolution is found in na and ree rich apatite apatite melt partition coefficients for la ce nd sm dy y and yb are calculated for the augite syenite and nepheline syenites of the roof sequence the coefficients show the characteristic convex shape with a maximum around nd and sm using the calculated partition coefficients and the chemical composition of the na and ree rich apatite the ree content of a late aqpaitic melt in the roof sequence is estimated the shape of the chondrite normalised pattern is similar to that of a late arfvedsonite lujavrite dyke and steeper than the patterns of the primary magma

uranium metallogenesis of the peraluminous leucogranite from the pontivy rostrenen magmatic complex french armorican variscan belt the result of long term oxidized hydrothermal alteration during strike slip deformation in the french armorican variscan belt most of the economically significant hydrothermal u deposits are spatially associated with peraluminous leucogranites emplaced along the south armorican shear zone sasz a dextral lithospheric scale wrench fault that recorded ductile deformation from ca 315 to 300 ma in the pontivy rostrenen complex a composite intrusion the u mineralization is spatially associated with brittle structures related to deformation along the sasz in contrast to monzogranite and quartz monzodiorite 3 3 the leucogranite samples are characterized by highly variable u contents 3 to 27 ppm and th u ratios 0 1 to 5 suggesting that the crystallization of magmatic uranium oxide in the more evolved facies was followed by uranium oxide leaching during hydrothermal alteration and or surface weathering u pb dating of uranium oxides from the deposits reveals that they mostly formed between ca 300 and 270 ma in monzogranite and quartz monzodiorite apatite grains display magmatic textures and provide u pb ages of ca 315 ma reflecting the time of emplacement of the intrusions in contrast apatite grains from the leucogranite display textural geochemical and geochronological evidences for interaction with u rich oxidized hydrothermal fluids contemporaneously with u mineralizing events from 300 to 270 ma infiltration of surface derived oxidized fluids leached magmatic uranium oxide from fertile leucogranite and formed u deposits this phenomenon was sustained by brittle deformation and by the persistence of thermal anomalies associated with u rich granitic bodies

britholite monazite ree carbonates and calcite products of hydrothermal alteration of allanite and apatite in a type granite from stupne western carpathians slovakia abstract an uncommon assemblage of primary and secondary accessory ree minerals was identified in a permian a type granite clast in polymict conglomerates intercalated in the cretaceous flysch sequence of the pieniny klippen belt western carpathians northwest slovakia a detailed electron microprobe study of the granite reveals extensive subsolidus alteration of primary magmatic allanite ce to ferriallanite ce and fluorapatite the y ce rich fluorapatite was replaced by the dissolution reprecipitation process to the britholite group mineral members fluorbritholite y britholite y fluorcalciobritholite and its hydroxyl dominant analogue calciobritholite britholite y contains up to 5 2 wt tho2 0 15 apfu th the highest th content yet reported in naturally occurring y dominant britholites moreover the alteration of ferri allanite ce resulted to complex pseudomorphs and overgrowths including mainly ree carbonate phases synchysite ce to its hydroxyl dominant analogue hydroxylsynchysite ce bastnasite ce and calcite rarely monazite ce epidote clinochlore titanite tio2 phase and pseudorutile in some cases secondary carbonate minerals mainly synchysite and calcite replaced a substantial part of former allanite crystals moreover primary magmatic biotite annite was partly transformed to acicular stilpnomelane textural and compositional data indicate extensive replacement and breakdown of the primary magmatic allanite and apatite by aqueous fluids rich in fluorine and carbon liberated during a younger post magmatic low temperature hydrothermal metamorphic overprint of the granite

multi method radiometric dating of volcano sedimentary layers from northern italy age and duration of the priabonian stage abstract a comparison between conventional k ar biotite ages and fission track zircon and apatite and u pb zircon ages obtained from stratigraphically well constrained priabonian late eocene volcano sedimentary deposits of northern italy is presented two sections at priabona one level and possagno two levels were dated the application of fission track dating appears fruitful for obtaining reasonably precise 4 to 5 2 errors ages useful for time scale calibration the concordancy of apatite and zircon fission track ages and the reproducibility of results provide the time of volcanic eruption and deposition the u pb analysis of the zircons has not been unsuccessful but discordancy does not permit accurate dating significant dates obtained from possagno are k ar method 35 0 0 5 ma duplicate analysis on k rich biotite from the same level fission track dating method 35 8 1 4 ma weighted mean age on 2 apatite and 3 zircon separates from the same level u pb method 36 7 1 0 ma maximum age of discordant zircons from the same level the comparison between the present results and recent multi method and multi laboratory results obtained from time equivalent priabonian late eocene biotite rich layers from the apennines shows perfect agreement and supports the location of a priabonian stage between about 37 5 ma and about 33 7 0 5 ma the alternative ages preferred by the decade of north american geology convention should be abandoned and a large portion of this scale revised accordingly

apatite monazite relations in the kiirunavaara magnetite apatite ore northern sweden the magnetite apatite ores in the kiruna area northern sweden are generally considered to be of magmatic origin formed in a subvolcanic volcanic environment during the early proterozoic they are thought to have crystallised from volatile rich iron oxide magmas derived by immiscibility in calc alkaline to slightly alkaline parental magmas three major morphological types of the magnetite apatite ore primary brecciated and banded have been investigated for textural relations and mineral chemistry using transmitted light back scattered electron imaging bse electron microprobe analysis empa and laser ablation inductively coupled plasma mass spectrometry la icpms in all three types th and u poor monazite is present as small inclusions in the apatite larger up to 150 m recrystallised monazite grains both along apatite grain boundaries and intergrown with magnetite and silicate minerals are present in the brecciated and banded samples primary apatite grains without monazite inclusions are generally enriched in light rare earth elements lrees together with na and si petrological and mineralogical evidence suggest that the kiruna magnetite apatite ore experienced successive stages of fluid rock interaction the first stage occurred under high temperature conditions 700 800 c shortly after emplacement and crystallisation of the ore magmas and involved concentrated probably cl dominated brines expelled from the magma this fluid is held to be responsible for the nucleation of the numerous small monazite inclusions within the apatite due to high temperature leaching of na and si while the lrees were concentrated in the monazite the large monazite grains in the brecciated and banded samples are proposed to be the product of recrystallisation from the much smaller monazite inclusions during greenschist facies metamorphism t 300 400 c fluids from the surrounding country rock caused strong lree na si depletion along apatite grain boundaries and cracks in the apatite lrees were either redeposited as monazite grains along apatite grain boundaries or were flushed out of the ore this fluid interaction also introduced the silicate components responsible for the interstitial formation of allanite talc tremolite chlorite serpentine muscovite quartz and carbonates along apatite grain boundaries

fluid induced nucleation of y ree phosphate minerals within apatite nature and experiment part i chlorapatite this study investigates chlorapatite ideally ca10 po4 6cl2 from two spatially separated locations in the odegardens verk apatite mine bamble sector se norway which was partially metasomatized under amphibolite facies conditions relative to the original chlorapatite metasomatized areas in sample dl136 are enriched in oh and f depleted in na si and y ree and contain numerous inclusions 1 15 m of monazite and xenotime in contrast metasomatized areas in sample tn174 are enriched in f and si depleted in na show y ree abundances similar to the original chlorapatite and host only a few monazite and xenotime grains in order to define the role of fluids in the formation of y ree phosphate minerals associated with apatite a series of experiments covering wide ranges of temperature 900 300 c and pressure 1000 500 mpa for a series of fluid compositions pure h2o a 50 50 molar mix of h2o and caf2 and co2 with 1 2 wt h2o were conducted on unaltered chlorapatite from the odegardens verk in the h2o experiments features due to metasomatic alteration depletion in na si and y ree as well as numerous monazite and xenotime inclusions as observed in the natural sample dl136 were fully reproduced monazite and xenotime grains were also observed growing on the surface of the apatite in dissolution embayments in metasomatized areas in the 50 50 caf2 h2o experiments metasomatized regions are strongly enriched in f and si depleted in na show unchanged y ree abundances and contain only a very few small monazite and xenotime grains similar to what was observed in sample tn174 natural and experimental observation imply the presence of two coupled substitutions na y ree 3 2 ca2 and si4 y ree 3 p5 ca2 in the case of dl136 and h2o fluid experiments na and si4 went into solution whereas the released y ree contributed to the growth of monazite and xenotime within the metasomatized apatite structure for sample tn174 and the 50 50 caf2 h2o fluid experiments na in apatite became depleted but si was enriched thereby stabilizing the y ree in the now recrystallized fluor hydroxylapatite structure which retarded the growth of monazite or xenotime inclusions the basic conclusion of this study is that nucleation of monazite and xenotime in the metasomatized chlorapatite is principally a function of the composition of the infiltrating fluid and to a much lesser extent temperature and pressure

in situ major trace elements and sr nd isotopic compositions of apatite from the luming porphyry mo deposit ne china constraints on the petrogenetic metallogenic features abstract apatite is an important accessory mineral in granitic rocks and can record important petrogenetic metallogenic information in particular magmatic apatite can provide information on the volatile composition and magma source of the ore forming rocks in porphyry deposits this work focuses on magmatic apatite within the ore forming intrusion of the luming super large porphyry mo deposit we use electron probe micro analyzer epma and laser ablation multi collector inductively coupled plasma mass spectrometry la mc icp ms analytical methods to analyze the major and trace element and sr nd isotopic compositions of the apatite the results show that the apatite grains are magmatic apatite classified as fluorapatite the trace element patterns of the apatites feature clearly negative sr ba and zr anomalies and ba nb sr zr and eu depletions that are more distinct than those in the granite porphyry and monzogranite in the luming deposit the apatites exhibit slight lree enrichment and distinctly negative eu anomalies the positive eu eu eu ga correlation and the strongly negative eu anomaly indicate that the magma of this granite porphyry may have been in a relatively reductive state the apatites also indicate that the granite porphyry is a non adakitic rock which is consistent with the whole rock geochemical characteristics furthermore the apatites feature low sr contents and eu values and high f cl ratios similar to the characteristics of typical mo deposits the 87 rb 86 sr and 87 sr 86 sr ratios of the apatites are 0 012811 0 037958 and 0 710897 0 714423 respectively the 87 sr 86 sr i i sr values are 0 710865 0 721183 the 147 sm 144 nd and 143 nd 144 nd ratios are 0 132166 0 225171 and 0 512520 0 512681 respectively the end t values are 1 78 0 21 and the two stage nd model ages are 949 1065 ma the approximately positive end t values and young nd model ages of the apatite are similar to those of the ore forming rocks in early jurassic mo deposits in ne china indicating that these rocks shared the same magma source which originated from the partial melting of juvenile crust