very preliminary reference moon model abstract the deep structure of the moon is a missing piece to understand the formation and evolution of the earth moon system despite the great amount of information brought by the apollo passive seismic experiment alsep the lunar structure below deep moonquakes which occur around 900 km depth remains largely unknown we construct a reference moon model which incorporates physical constraints and fits both geodesic lunar mass and polar moment of inertia and love numbers and seismological body wave arrivals measured by apollo network data in this model the core radius is constrained by the detection of s waves reflected from the core in a first step for each core radius a radial model of the lunar interior including p and s wave velocities and density is inverted from seismic and geodesic data in a second step the core radius is determined from the detection of shear waves reflected on the lunar core by waveform stacking of deep moonquake apollo records this detection has been made possible by careful data selection and processing including a correction of the gain of horizontal sensors based on the principle of energy equipartition inside the coda of lunar seismic records and a precise alignment of sh waveforms by a non linear inversion method the very preliminary reference moon model vpremoon obtained here has a core radius of 380 40 km and an average core mass density of 5200 1000 kg m 3 the large error bars on these estimates are due to the poorly constrained s wave velocity profile at the base of the mantle and to mislocation errors of deep moonquakes the detection of horizontally polarized s waves reflected from the core and the absence of detection of vertically polarized s waves favour a liquid state in the outermost part of the core all these results are consistent within their error bars with previous estimates based on lunar rotation dissipation williams et al 2001 and on lunar induced magnetic moment hood et al 1999

constitution of the moon 2 composition and seismic properties of the lower mantle abstract to constrain the composition of the moon we have calculated the stable phase assemblages and their seismic properties by the method of minimization of gibbs free energy to determine whether various compositional models are consistent with the seismic observations for the lunar lower mantle at depths between 500 and 1000 km p wave and s wave velocities have been calculated for a series of proposed bulk composition models compositional models for the moon impactor composition orgueil composition etc and earth like compositions lherzolite and pyrolite have been considered it is found that impactor and orgueil models are unlikely for the lower mantle within reasonable temperature adjustment in the temperature profile all of the terrestrial compositional models come close to the seismic data below the 500 km discontinuity it is found that a composition enriched in al 2 o 3 up to about 6 wt and having pyrolite content of the other major oxides lunar pyrolite is adequate to describe the seismic properties of the lunar lower mantle within the uncertainty of calculations and resolution of seismic data an al rich model with a terrestrial ol px ratio and unusually enriched in garnet gives the best fit to the lunar lower mantle seismic properties despite the uncertainty of the seismic data it is shown that none of the analysed compositional models satisfies the seismic constraints simultaneously in the middle and lower mantle phase changes in any model considered are not able to explain the nature of the 500 km discontinuity it is concluded that the lunar mantle is chemically stratified

the competition between thermal contraction and differentiation in the stress history of the moon the scarcity of both extension and compression features on the moon strongly constrains the history of the lunar radius to variations of less than 1 km over the past 3 8 gyr this limit has traditionally been interpreted as requiring a delicate balance between thermal contraction of the near surface and expansion of a substantial cold interior region recent theories of lunar origin e g giant impact in contrast favor a hot initial state we propose that a reconciliation may be possible by taking account of the volume change v v d due to differentiation we calculate stp densities based on simplified normative mineralogies for a suite of estimates of the bulk lunar composition of primary lunar basalt and of the residuum left when the maximum amount of the latter is extracted from the former typically v v d 2 to 5 an expansion equivalent to heating by 10 3 k provided the timing of differentiation is correct one might offset the cooling of a magma ocean as much as 630 km deep by differentiation of the remainder of the moon which need not start much below the solidus temperature a large but not impossible amount of gabbroic melt production is implied 100 times the volume of mare basalts known to have been extruded we do not address the detailed genetic relationship of this melt to the basalts observed on the lunar surface but point out that it need not have reached the surface directly or even have entered the crust in order for the expansion to have occurred to assess the timing of melt formation we investigate a simple conductive lunar thermal model which takes account of both v v d and thermal contraction our initial state is characterized by a central temperature t c and a depth z 0 above which the material derived from the magma ocean is already at the solidus and is not suceptible to volume changes upon further differentiation we find a range of models satisfying the limits on radius increase and decrease the hottest has t c 1210 k z 0 400 km without v v d we would need a larger or colder or both core e g t c 700 k for z0 200 400 km in agreement with previous investigators our modeling thus lends credence to the idea that the moon could have been initially 50 molten with the remainder relatively close to the solidus and yet experienced little volume change over the last 3 8 gyr

improved gravity field of the moon from lunar prospector an improved gravity model from doppler tracking of the lunar prospector lp spacecraft reveals three new large mass concentrations mascons on the nearside of the moon beneath the impact basins mare humboltianum mendel ryberg and schiller zucchius where the latter basin has no visible mare fill although there is no direct measurement of the lunar farside gravity lp partially resolves four mascons in the large farside basins of hertzsprung coulomb sarton freundlich sharonov and mare moscoviense the center of each of these basins contains a gravity maximum relative to the surrounding basin the improved normalized polar moment of inertia 0 3932 0 0002 is consistent with an iron core with a radius of 220 to 450 kilometers

constitution of the moon 3 composition of middle mantle from seismic data abstract the constitution of the lunar middle mantle which is located between two prominent discontinuities at depths of 270 and 500 km has been investigated by a method of thermodynamic modeling on the basis of the thermoseism data base self consistent phase equilibrium assemblages and synthetic seismic profiles have been calculated for various geochemical models with different contents of the major petrogenic oxides it is shown that none of the analyzed compositional models satisfies the seismic velocity profiles simulataneously in the middle and lower mantle phase changes in any petrological model considered do not explain the nature of the 500 km discontinuity pyroxenite models having 50 52 sio2 and 15 16 feo mg number 74 76 have the best fit to the middle mantle mean velocities of nakamura j geophys res 88 677 686 1983 and satisfy the mean density and lower mantle density constraints these results and the calculations of kuskov and fabrichnaya phys earth planet inter 83 197 216 1994 strongly reinforce the case for a chemically stratified moon interior

pliocene pleistocene vegetational and climatic evolution of the south central mediterranean abstract the vegetational history of the south central mediterranean clearly reflects the major global climatic changes of the last four million years a mediterranean type climate characterized by strong seasonality and a dry summer may have existed in this region during the early pliocene a short term climatic cooling at approximately 3 2 ma resulted in the temporary establishment of a humidity demanding flora the onset of major northern hemisphere glaciation at approximately 2 4 ma initiated an alternation between humid glacial and dry interglacial conditions vegetational differences between this region and the north west mediterranean indicate that distinct latitudinal climatic gradients probably existed in the mediterranean during the pliocene early pleistocene

a seismic model of the lunar mantle and constraints on temperature and mineralogy abstract we determine seismic profiles of the moon s interior using travel times obtained from a re analysis of the apollo data due to the limited number of quakes and stations travel times errors were determined and used in the inversions our model has a mean crustal thickness of about 30 km in the region of the apollo network with a 10 km zone of brecciation below the crust mean values of seismic velocities in the upper mantle are rather well constrained and are in the range 7 6 7 8 and 4 35 4 45 km s 1 for p and s waves respectively velocity variations in the middle mantle are less well defined in the zone of deep moonquakes below 740 km depth velocities increase slightly to 8 15 0 23 and 4 5 0 10 km s 1 for p and s waves respectively we analyse the seismic profile in term of mineralogy and temperature constraints our preferred models are a pyroxenite model for the upper mantle and a magnesian rich model for the lower mantle with increasing mg with depth we find temperatures of about 1100 k elastic lithosphere limit and 1500 k thermal lithosphere limit for radii of about 1400 and 1000 km respectively and show that the lunar mantle is probably depleted in th and u by at least 70 compared to an earth reference value of 25 7 ppb u for a crustal thickness of 40 km with a mean 1010 ppb th concentration we then find bulk th and u abundances comparable to and possibly lower than currently accepted terrestrial values

rare earth element mobility at constant inter ree ratios in the alteration zone at the phelps dodge massive sulphide deposit matagami quebec rare earth elements ree from la to ho were mobile and enriched in hydrothermally altered rocks below the archean phelps dodge cu zn volcanogenic massive sulphide deposit in northwestern quebec largest net enrichment was in the moderately altered quartz chlorite zone where la concentration increased six fold and lanybn steepened from 1 9 to 13 0 the intensely altered chloritite zone had both minor net ree enrichment and depletion yb and lu were immobile throughout both zones the mobile ree were added and subtracted in constant chondrite normalized inter ree proportions 1 0 la 0 79 ce 0 57 nd 0 49 sm 0 01 eu 0 10 tb and 0 02 hb small additions of eu relative to generally larger additions of lree and tb produced enhanced negative eu anomalies the ree were mobilized at the hot 300 c core of the alteration system and deposited at the cooler periphery other sites of intense alteration and water rock interaction display similar ree changes indicating that selective ree enrichment at constant inter ree ratios is a widespread phenomenon

aragonite stromatolitic buildups from santorini aegean sea greece geochemical and palaeontological constraints of the caldera palaeoenvironment prior to the minoan eruption ca 3600 yr bp this study received financial support from projects cgl2008 00594 and cgl2011 2348 plan nacional ministerio de ciencia e innovacion spain pa additional funding for analyses was provided by the mexican in103211 papiit project cc

rare earth element geochemistry of clastic and chemical metasedimentary rocks associated with hydrothermal sulphide mineralisation in the olary block south australia abstract analysis of a variety of rock types from the south australian portion of the lower to middle proterozoic willyama inliers by icp ms demonstrate that primary rare earth element ree distributions remained essentially unchanged despite multiphase deformation and amphibolite grade metamorphism variable trends of preferential ree mobilisation are observed only where large amounts of fluid caused the rock to undergo strong retrogression and or hydrothermal alteration except for these conditions ree can be considered immobile and their distribution is generally independent of mineralogy thus providing a powerful tool for the characterisation of provenance of protoliths in a high grade metamorphic terrain ree signatures and other geochemical constraints of some volcanogenic sediments for example point to an andesitic parentage suggesting bimodal and gradually changing volcanism occurring in a developing intracontinental rift zone ree distributions in metasediments associated with sulphide mineralisation reflect both physico chemical characteristics of the ore bearing fluids and rock compositions comparison of their ree profiles allows discrimination between a strata bound redox controlled deposits b exhalative mineralisation and c epigenetic vein type mineralisation ree distributions in the analysed rocks are in agreement with other lines of textural and geochemical evidence for that limited syn tectonic remobilisation low fluid rock ratios unchanged primary ree signatures but widespread late stage mobilisation of sulphides high fluid rock ratios selective mobilisation of ree occurred in the olary block ree signatures of exhalative precipitates associated with sulphide mineralisation do not show a systematic stratigraphic variation but are indicative of fluctuating f o 2 conditions over short distances and display only moderately positive eu anomalies this contrasts with findings for the adjacent broken hill block and highlights the dissimilarities of ore formation processes that were active in the olary and the broken hill block as well as the depositional differences between the two blocks

lunar composition a geophysical and petrological synthesis lunar compositional constraints are derived on the basis of geophysical data in particular the lunar seismic model as revised by nakamura and petrological arguments only in the case of extreme assumptions can critical aspects of bulk lunar composition be demonstrated to be equivalent to the present day terrestrial mantle specifically the moon has an mg number that is too low and an alumina abundance that is too high over a broad range of crustal densities the presence of a metallic core at least 150 km in radius is necessary to reconcile the upper mantle lunar seismic model with mass and moment of inertia constraints a significant seismic discontinuity at 500 km depth may mark the lowest extent of early lunar differentiation possibly representing a transition between highly fractionated upper mantle and less fractionated perhaps even primordial middle lower mantle

rare earth element mobility around the volcanogenic polymentallic massive sulfide deposit at que river tasmania australia abstract the que river volcanogenic base and precious metal deposit is located in the cambrian mt read volcanics of western tasmania the host andesites and dacites adjacent to mineralization have been hydrothermally altered during mineralization and the entire sequence has undergone devonian regional prehnite pumpellyite facies metamorphism rocks petrographically recognizable as andesites exhibit chondrite normalized ree patterns similar to modern orogenic high k andesitic rocks with ce yb n ratios ranging from 6 4 to 8 6 dacites are more fractionated with ce yb n ranging from 10 6 to 16 0 like the andesites the dacites are characterized by negative eu anomalies eu eu 0 73 0 85 except for a more extreme eu anomaly in one sample eu eu 0 57 polymict volcaniclastic rocks have patterns very similar to those of the andesites the chondrite normalized ree patterns for the hydrothermally altered volcanics fall into three groups that can also be distinguished petrographically a single chloriterich sample has a substantial eu anomaly and shows less relative depletion in the middle ree than do either the andesites or the dacites highly silicified samples are all characterized by large negative eu anomalies eu eu 0 37 0 46 and many are relatively unfractionated with ce yb n ratios ranging from 3 5 to 7 7 a third group of samples characterized by the development of phengitic mica and carbonate show ree patterns similar to the andesites although their eu anomalies are generally smaller a sample of massive zn 1bpb ore has very low ree abundances showing light ree enrichment and a small negative eu anomaly eu eu 0 82 massive pyrite has a similar pattern except for higher overall abundances and a small positive eu anomaly eu eu 1 10 except for the eu anomalies the andesites and dacites show no evidence for ree mobility eu anomalies in the andesites are probably due to alteration of phenocrystic plagioclase and subsequent removal of divalent eu substantial ree mobility has occurred in the hydrothermally altered volcanic rocks the degree of mobility correlating with alteration style and intensity eu has been leached from both former plagioclase phenocrysts and the groundmass some of the eu leached from zones of the most intense alteration may have been redeposited in lower temperature more distal alteration zones

the willyama supergroup in the broken hill and euriowie blocks new south wales abstract the willyama supergroup consists of highly deformed metasedimentary schists and gneisses with abundant quartzofeldspathic gneisses lesser basic gneisses and minor lode rocks prograde metamorphism ranged from andalusite through sillimanite to granulite grade radiometric dating in the broken hill block indicates separation of the source of the quartzo feldspathic gneisses from the mantle at 2300 2100 ma a rb sr model source age of 1820 60 ma has been interpreted as the maximum age of deposition deformation d 1 and or d 2 was coincident with high grade metamorphism at 1660 10 ma minor mundi mundi type granitoids and some pegmatites were intruded at 1490 20 ma minor pyroxenites at 561 7 ma dolerite dykes soon after and zoned pegmatites at 500 ma in association with the delamerian orogeny which reactivated retrograde schist zones at 520 40 ma subsequent history mostly comprises faulting weathering uplift and erosion the willyama supergroup has an estimated total thickness of 7 9 km with neither top nor basement exposed no unconformities have been recognized in the sequence the supergroup was deposited in a deepening environment passing upward from sandy facies to more shaly and fine sandy facies and from interpreted bimodal acid basic volcanics to non volcanic facies the metasediments have been interpreted as shelf sediments overlain by deeper water turbidites and minor contourites recently they have been reinterpreted as shallow marine with the quartzo feldspathic gneisses interpreted as fluvio deltaic arkoses in this paper the sequence to the top of thackaringa group is interpreted as mainly fluvio deltaic and lacustrine the broken hill group and sundown group are interpreted as shallow marine the paragon group may have comprised shelf muds overlain by delta front and lacustrine sediments in turn overlain by deeper water fine grained turbidites the broken hill orebody near the top of broken hill group consists of a series of stacked lenses much recent work has concluded that the deposit is volcanic exhalative in origin probably formed from seawater convected through the sequence and driven by heat from high level magma chambers however some features of the deposit are more appropriate to a sedimentary exhalative origin and models have been proposed involving seismic pumping of connate water with ore deposition on or below the seafloor devolatilization of the mantle has been proposed as a source of ore constituents deposition may have occurred in a narrow ne sw trending seafloor depression the willyama supergroup was probably deposited in a rift zone with thin crust the basic gneisses are interpreted as fe rich tholeiites similar to basalts from some oceanic spreading ridges the intense folding post folding leucogranitic intrusions and extensive granulite amphibolite facies metamorphism could have resulted from a collision following subduction however there is no direct evidence of oceanic crust or subduction and the low pressure metamorphic path does not suit a collision model the rocks were probably deposited in a continental rift with some similarities to those interpreted for proterozoic fold belts in northern australia

trace element geochemistry of ore associated and barren felsic metavolcanic rocks in the superior province canada reply archaean felsic metavolcanic rocks in the superior province of the canadian shield may be divided into three major groups on the basis of trace element abundances and ratios 1 fi felsic metavolcanic rocks are dacites and rhyodacites characterized by steep ree patterns with weakly negative to moderately positive eu anomalies high zr y low abundances of high field strength elements e g hree y zr hf and high abundances of sr examples occur in the bowman subgroup and skead group in the abitibi belt in the kakagi lake lake of the woods shoal lake and sturgeon lake areas of the wabigoon belt and in the confederation lake area of the uchi belt none of these horizons as known hosts base metal sulphide deposits 2 fii felsic metavolcanic rocks are rhyodacites and rhyolites characterized by gently sloping ree patterns with variable eu anomalies moderate zr y and intermediate abundances of hfs elements and sr examples occur in the misema subgroup of the abitibi belt in the wabigoon lake a

the moon a taylor perspective we address several current lunar problems the data suggest that the moon likely possesses an fe rich metallic core a few percent of lunar volume although definitive proof is lacking refractory elements appear to be enriched relative both to the composition of the primordial solar nebula ci and the earth very volatile elements appear to be depleted uniformly at high levels we adopt the single impact hypothesis for lunar origin which formed a high temperature silicate vapor disk mostly of metal poor silicate material from an impactor theia that was already depleted in volatiles we speculate that the curious lunar bulk composition resulted from condensation from high temperature vapor at around a few earth radii this could produce an enriched refractory element composition that cut off below 1000 k producing a uniform depletion in very volatile elements

does the moon possess a molten core probing the deep lunar interior using results from llr and lunar prospector 1 it is the main purpose of this study to examine the deeper structure of the moon in the light of four numbers these are lunar mass m mean moment of inertia i second degree tidal love number k2 and the quality factor q accounting for tidal dissipation within the solid body of the moon the former two have been measured by lunar prospector to high precision and more than 30 years of lunar laser ranging llr data have led to an estimate of the second degree tidal love number and quality factor the inverse problem dealt with here of obtaining information on the lunar density and s wave velocity profile from the four numbers follows our earlier investigations by employing an inverse monte carlo sampling method we present a novel way of analyzing the outcome using the bayes factor the advantage lies in the fact that rather than just looking at a subset of sampled models we investigate all the information sampled in different runs i e take into account all samples in order to estimate their relative plausibility the most likely outcome of our study based on the data their uncertainties and prior information is a central core with a most probable s wave velocity close to 0 km s density of 7 2 g cm3 and radius of about 350 km this is interpreted as implying the presence of a molten or partially molten fe core in line with evidence presented earlier using llr regarding the dissipation within the moon

the constitution and structure of the lunar interior the current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period missions of the 1960s including the rangers surveyors and lunar orbiters as well as earth based telescopic studies laid the groundwork for the apollo program and provided a basic understanding of the surface its stratigraphy and chronology through a combination of remote sensing surface exploration and sample return the apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean in particular the discovery of anorthite clasts in the returned samples led to the view that a large portion of the moon was initially molten and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle and plagioclase flotation cumulates that make up the crust smith et al 1970 wood et al 1970 this model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the moon the intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the moon s interior much of this new knowledge is a direct result of data acquired from the successful clementine and lunar prospector missions as well as the analysis of new lunar meteorites as will be seen results from these studies have led to many fundamental amendments to the magma ocean model much of what we know from sample analyses has been previously summarized elsewhere and only their most important aspects will be discussed in this chapter the reader is referred to the relevant chapters in the books basaltic volcanism on the terrestrial planets basaltic volcanism study project 1981 the

behaviour of rare earth elements during hydrothermal alteration at the buena esperanza copper silver deposit northern chile abstract a study of the ree behaviour in alteration zones of the buena esperanza subvolcanic cu ag deposit located in the coastal range of northern chile reveals that the elements are mobile in the rocks during alteration the ore forming process developed in three different stages of alteration mineralization the hydrothermal alteration of the early and middle stages affected basaltic fragments of a breccia pipe la and ce were leached from the rock fragments located at the bottom and at the middle part of the breccia pipe and partly redeposited at the top during alteration sm eu and tb were released selectively and the heavy ree behaved as relatively immobile elements sericite is the most important alteration mineral for fixing the ree during this stage the incoming fluids had low ree contents the late stage of hydrothermal alteration happened simultaneously with the intrusion of a gabbroic volcanic neck affecting mainly these subvolcanic rocks ree patterns of samples from the top and bottom of the alteration zone exhibit roughly parallel trends but are systematically enriched in ree in comparison to unaltered samples this enrichment seems to be more intensive at the top of the altered area coinciding with the enrichment of rb k and cu in these rocks epidote plays the most important role for fixing this hydrothermal input of ree during the latest stage of alteration

crustal thickness of the moon new constraints from gravity inversions using polyhedral shape models a new method is presented for estimating crustal thickness from gravity and topography data on the moon by calculating analytically the exterior gravitational field for a set of arbitrarily shaped polyhedra relief along the crust mantle interface can be inverted for that satisfies the observational constraints as this method does not rely upon filtering the bouguer anomaly which was required with previous inversions performed in the spherical harmonic domain and as the dramatic variations in spatial quality of the lunar gravity field are taken into account our crustal thickness model more faithfully represents the available data using our model results we investigate various aspects of the prominent nearside impact basins the crustal thickness in the central portion of the orientale and crisium basins is found to be close to zero suggesting that these basins could have conceivably excavated into the lunar mantle furthermore given our uncertain knowledge of the density of the crust and mantle it is possible that the humorum humboldtianum nectaris and smythii basins could have excavated all the way through the crust as well the crustal structure for most of the young impact basins implies a depth diameter ratio of about 0 08 for their excavation cavities as noted in previous studies however the crustal structure of imbrium and serenitatis is anomalous which is conceivably a result of enhanced rates of post impact viscous relaxation caused by the proximity of these basins to the procellarum kreep terrane impact basins older than smythii show little or no evidence for crustal thinning suggesting that these ancient basins were also affected by high rates of viscous relaxation resulting from higher crustal temperatures early in the moon s evolution the lithosphere beneath many young basins is found to be supporting a downward directed force even after the load associated with the mare basalts is removed and this is plausibly attributed to superisostatic uplift of the crust mantle interface those basins that are close to achieving a pre mare isostatic state are generally found to reside within or close to the procellarum kreep terrane

integrated magnetostratigraphy and biostratigraphy of the upper pliocene lower pleistocene from the monte singa and crotone areas in calabria italy the results of a detailed magnetostratigraphic and biostratigraphic study of late pliocene to early pleistocene marine marl sequences from the monte singa and crotone areas in calabria italy are presented the magnetostratigraphy from the monte singa sequence ranges from below the gauss matuyama boundary up to and including the lower olduvai boundary normal polarities at a level corresponding to isotope stage 81 most probably represent the r union subchron from the lower olduvai boundary upward a reliable magnetostratigraphy could not be established due to increased weathering of the marls resulting in mainly secondary magnetizations the magnetostratigraphy from the composite sequence of the crotone area belongs to a large part of the matuyama chron and includes the olduvai subchron the position of the lower and upper boundaries of the olduvai subzone could be established more precisely than from earlier results moreover the upper boundary of the olduvai subzone poses an ambiguity a relatively long normal polarity interval representing the main olduvai subchron and corresponding to a duration of 115 ka is followed by a short 30 ka reversed subchron and the short 15 ka normal vrica subchron another option and more in accordance with the duration of the olduvai subchron in literature would be to consider the complete n r n polarity succession with a total duration of 160 ka as representing the olduvai subchron implying that this olduvai subchron has a short reversed interval in its upper part linear interpolation and extrapolation yield ages for the most important late pliocene early pleistocene biostratigraphic datum levels an age of 1 69 ma is found for the pliocene pleistocene boundary using the conventional polarity time scale dated with radiometric results however hilgen 1 in correlating the sapropel groups and patterns to the precession curve of the earth s orbit obtained significantly different ages for the polarity transitions of the present study according to this astronomically calibrated polarity time scale the age of the pliocene pleistocene boundary is 1 81 ma

fluctuations in a magmatic sulphur isotope signature from the pinnacles mine new south wales australia sulphur isotopic compositions of 29 sulphide samples from the broken hill type pinnacles deposit nsw are found to cluster at 0 mean 0 8 the restricted range of the 34s values between 3 5 and 3 7 with a mean of 0 8 is interpreted as reflecting partial oxidation of a dominantly magmatic sulphur source 34s data for galena samples fall into two groups 1 isotopically heavier galenas range 0 7 to 0 0 mean 0 4 which come mainly from the footwall zn lode and 2 isotopically lighter galenas range 3 5 to 0 8 mean 2 2 which are from the main pb lode sphalerite pyrrhotite and chalcopyrite have slightly heavier isotopic compositions range 1 6 to 3 7 mean 0 3 but exhibit the same stratigraphic differentiation these data are interpreted as representing fluctuating conditions at the site of ore deposition in which upwelling hydrothermal fluids were subject to increasing fo2 and decreasing temperature with time

anorogenic felsic magmatism rift sedimentation and giant proterozoic pb zn deposits the giant lead deposits that developed after 1 8 ga in australia north america and africa are absent in the earlier geologic record these proterozoic lead zinc deposits were all preceded by major outbreaks of anorogenic felsic magmatism that brought significant amounts of lead rich material 30 ppm to the surface of proterozoic cratons erosion of these volcanics apparently transferred major quantities of the lead to rift basins where giant lead deposits were generated all known giant proterozoic sediment hosted lead zinc deposits more than 50 mt of lead metal are explained by a model that is supported by sm nd data relevant to mantle separation ages of volcanics and the metasedimentary source rocks for the lead ores

did the giant broken hill australia zn pb ag deposit melt abstract recent published research has proposed that some metamorphosed massive sulfide deposits including the broken hill deposit australia have partially melted here we discuss the evidence for and against this process the broken hill deposit is located in the curnamona craton within a rift in an apparent upward coarsening sequence of clastic metasediments into which paleoproterozoic mafic and felsic melts intruded the deposit was metamorphosed to granulite facies conditions 750 800 c and 5 6 kbar and was subjected to at least five periods of deformation at peak p t conditions a melt phase was produced in silicate rocks especially granitoids and psammopelites and in ore characterized by the systems cu as s ag pb s ag sb as s cu sb pb s sb as s cu sb s and fe as s however the proportion of minerals in these s bearing systems is insignificant 2 feo mno cao al 2 o 3 p 2 o 5 co 2 zns pbs fes feass feas 2 which is the most relevant system to broken hill ores p t conditions were never high enough to produce a melt phase in this system authors arguing for sulfide rock melting suggest that mn rich lithologies garnetite and quartz garnetite which are intimately associated with the pb rich ores at the broken hill deposit were produced by a reaction between mn rich sphalerite and aluminous wall rocks however to produce such rocks would require mn contents of sphalerite compositions that are unrealistically high and yet to be found in nature moreover the implication of the melt model is that wherever mn rich quartz garnetite and garnetite are found sphalerite should be located next to them this is clearly not the case the presence of polyphase sulfide inclusions within garnet in garnetite has also been considered by some in the literature to be sulfide melt inclusions with the implication that the enclosing garnet was a product of melting however we consider these sulfides to be products of hydrothermal processes during retrograde metamorphism it is impossible to form garnetite and quartz garnetite in rocks within the curnamona craton that formed at upper greenschist lower amphibolite facies conditions by partial melting p t conditions were too low we consider that the fe and mn component of garnetite and quartz garnetite are products of exhalation and inhalation at or near the sea floor and that these rocks are meta exhalites or meta inhalites some garnet rich rocks also formed by metasomatic processes throughout the protracted metamorphic history that affected the curnamona craton

geochemical constraints on the seismic properties of the lunar mantle abstract thermodynamic modeling of phase relations and physical properties in the na2o tio2 cao feo mgo al2o3 sio2 fe fes system and a monte carlo inversion procedure have been used to calculate the density and velocity distribution in the mantle and core radii of the moon from the mass and moment of inertia constraints from recent lunar prospector gravity measurements for the computation of the phase diagram for a given chemical composition we have used a method of minimization of the total gibbs free energy and self consistent thermodynamic data for minerals and solid solutions for the crustal thickness and density of 60 km and 3 0 g cm 3 the largest core radii are estimated to be 530 km for an fes troilite core 4 1 of total mass 490 km for a eutectic fe fes core 3 4 445 km for an fe 10 wt s core 2 9 and 350 km for an fe core 2 the existence of an fe fes core of intermediate radius of 250 400 km is compatible with recent lunar core information and lend support to a chemically stratified lunar mantle the sensitivity of density and seismic velocities to temperature pressure and composition variations is examined the modeling results indicate that we can determine the permissible density and velocity ranges in the zoned lunar mantle with confidence the maximum and minimum density changes at depths of the lunar mantle consistent with geochemical constraints and mass and moment of inertia requirements are found to be 3 22 g cm 3 3 44 g cm 3 at depths of 60 500 km and 3 34 g cm 3 3 52 g cm 3 at depths between 500 km and the core mantle boundary core free models of the moon are possible only if the lower mantle densities are between 3 49 and 3 52 g cm 3 20 wt feo wt the calculated field of seismic velocities in the zoned lunar mantle shows that over a broad range of mantle compositions temperatures and densities the maximum variations are as follows 4 23 km s 1 v s 4 69 km s 1 and 7 41 km s 1 v p 8 24 km s 1 at depths of 60 500 km and 4 24 km s 1 v s 4 64 km s 1 and 7 63 km s 1 v p 8 39 km s 1 at depths between 500 km and the core mantle boundary these petrologically and geophysically admissible ranges of velocities and densities may constitute a significant constraint for the analysis of internal structure of the moon using the apollo seismic data

age constraints on the proposed plio pleistocene boundary stratotype at vrica italy estimates1 4 of the age of the stratotype plio pleistocene boundary in italy range from 1 65 to 2 5 myr we aim here to clarify this dating confusion and we present new radiometric data on ashes from the proposed stratotype section vrica italy which indicate that the plio pleistocene boundary must be less than 2 myr old biostratigraphical criteria the first appearance datums fads and last appearance datums lads of plank tonic foraminifera and calcareous nannoplankton tied to the magnetic reversal chronology suggest that this boundary may be nearer to 1 7 myr attempts to make the boundary far older than this are without basis

composition volume changes during hydrothermal alteration of andesite at buttercup hill noranda district quebec abstract hydrothermally altered andesites in the upper member of the amulet formation at buttercup hill noranda quebec represent part of the aquifer and cap of a self sealing geothermal system that focussed the discharge of hydrothermal fluids during the formation of massive cu zn sulfide deposits five alteration facies are recognized 1 pervasive greenschist facies regional metamorphism least altered andesite 2 epidotization silicification 3 albitization silicification 4 chloritization 5 sericitization silicification alteration is localized on permeable zones such as amygdules fractures flow tops discordant breccia dikes and conformable breccia horizons epidotized silicified andesite is enriched in ca sr eu and depleted in mg and first transition series metals ftsm relative to least altered andesite albitized silicified andesite is significantly enriched in na and depleted in most ftsm relative to least altered andesite the abundances and inter element ratios of the rare earth elements ree and most high field strength elements hfs y zr th u hf ta are similar in least altered epidotized silicified and albitized silicified andesites the most silicified andesites are strongly enriched in na si strongly depleted in mg and divalent ftsm and slightly but systematically depleted in ree and most hfs elements serialized andesites were previously silicified they are very strongly enriched in k rb cs ba very strongly depleted in na ca sr eu and slightly depleted in light ree relative to silicified andesite chloritized andesitic rocks exhibit heavy ree and hfs element ratios similar to those of leastaltered andesite but are relatively strongly enriched in mg and divalent ftsm strongly depleted in si and large ion lithophile lil elements and slightly depleted in light ree the coupled behavior of the heavy ree and most hfs elements during epidotization albitization silicification chloritization and serialization suggests that they were inert during hydrothermal modification of the andesite mass balance calculations suggest that volume was conserved during epidotization silicification and albitization silicification but that intense silicification was accompanied by volume increases up to 30 percent

rare earth element distributions among coexisting granulite facies minerals scourian complex nw scotland the major rock forming mineral phases pyroxenes plagioclase garnet hornblende of a suite of granulite facies gneisses from the scourian complex nw scotland have been analyzed for their rare earth element ree content although host rock compositions range from felsic to ultramafic ree abundances and patterns for each mineral group show only limited variation the rees exhibit regular and consistent distribution patterns for each mineral which suggest together with major element and textural considerations that the observed distribution coefficients approach equilibrium total ree content follows the sequence hornblende clinopyroxene garnet plagioclase orthopyroxene and mass balance calculations show that even in the felsic gneisses 60 of the rees reside in the major rock forming minerals comparisons of both relative ree abundances and distribution coefficients with those in other rock types reveal a striking resemblance with patterns observed in mineral liquid pairs of dacitic rocks these similarities may have arisen during a partial melting episode in which granite granodiorite melts were generated and removed from the scourian complex leaving a residuum which is severely depleted in the incompatible elements including the rees

atlantic mediterranean water exchange during the late neocene the nature of water exchange between the mediterranean and the atlantic is examined for three time periods during the late neogene in order to assess the impact of flow patterns between these basins on bottom water conditions in the oceans the large volume of carbonates and evaporites deposited in the mediterranean during the messinian salinity crisis appears to have caused the open ocean to become more undersaturated in calcium carbonate resulting in increased dissolution of deep sea carbonates during the latest miocene during the earliest pliocene an estuarine type of flow existed between the atlantic and mediterranean waters entered the mediterranean at depth and flowed out at the surface benthic foraminiferal stable isotopic evidence from the north atlantic indicates that north atlantic deep water nadw was produced throughout the early pliocene and that the absence of saline mediterranean outflow did not have a significant effect on bottom water production eustatic lowering of sea level during the last glacial maximum 18 000 years b p reduced water exchange between the atlantic and the mediterranean as a result salinities in the mediterranean increased substantially but it seems unlikely that diminished nadw production during the last glacial episode can be attributed to a reduction in mediterranean outflow

rare earth element distribution in exhalites associated with broken hill type mineralisation at the pinnacles deposit new south wales australia abstract rare earth element ree concentrations in exhalites and pelites associated with strata bound base metal broken hill type mineralisation have been measured for the early proterozoic pinnacles deposit in western new south wales garnetites garnet rich rocks and sulphide rich garnet gahnite bearing rocks exhibit a wide variety of ree concentrations particularly lree and eu which cannot be related entirely to changes in mineralogy but show some correlation with stratigraphic position relative to the main orebody exhalites lying in the footwall to the mineralised rocks have negative eu anomalies and steep lree enriched patterns whereas exhalites in the hanging wall to the ores and silicate rich rocks from within the ore lenses have zero or positive eu anomalies and less lree enriched patterns hree have more consistent values throughout the deposit but in places are strongly depleted non mineralised pelites are slightly enriched in the ree relative to shale composite values and have negative eu anomalies it is argued in this paper that because the variations in data can be related to the stratigraphic location of samples relative to the orebodies that the observed ree distributions are due to fluctuations in ree concentrations in the primary exhalative fluids rather than differential mobilisation of ree during a second post depositional episode of hydrothermal alteration or mobilisation of the ree during prograde granulite facies metamorphism or retrograde amphibolite facies metamorphism which has affected the area the lack of association between metamorphic mineral assemblages and ree distribution and the absence of any homogenisation of the ree concentrations suggest that the data reflect the primary exhalative fluid composition and that the variations in ree data reflect changes in palaeoenvironmental conditions such as f o 2 and temperature a corollary to this conclusion is that there was minimal mobilisation of the ree during subsequent metamorphism

rare earth element distributions in uraninites implications for ore genesis abstract analysis of the rare earth element ree distributions in uraninites from a variety of hydrothermal mineral deposits indicates that wide variations are to be anticipated although crystal structure must exert a fundamental influence upon ree substitution in uraninite the present study suggests that other factors in particular hydrothermal fluid chemistry may be of equal importance total ree ree contents range from 15 000 ppm in uraninites from ultrametamorphic deposits to eu eu lree hree 0 08 1 10 they are interpreted to result from variations in the oxygen fugacity and the nature of the anionic complexes in the hydrothermal fluids responsible for ore transport additionally in uraniferous quartz pebble conglomerates the ree patterns of the detrital uraninites provide direct evidence regarding the provenance of these sedimentary u ores

mn ba hg mineralization at shallow submarine hydrothermal vents in bahia concepcion baja california sur mexico coastal submarine hydrothermal venting occurs on the west shore of the fault bounded bay of bahia concepcion along a stretch of about 700 m of rocky shoreline diffuse hydrothermal seepage of water and continuous gas bubbling mainly co2 and n2 take place through the sediment covered seafloor at shallow depth 5 to 15 m in addition at about 500 m se a cluster of hot springs occurs within the intertidal zone the temperature and ph of the hydrothermal fluids varies from 72 to 87 c and 5 95 to 6 02 in the submarine diffuse venting area and reaches 62 c and ph of 6 68 in the intertidal hot springs mn ba hg mineralization is presently forming as a result of the hydrothermal venting at the intertidal hot springs moss like crusts of manganese oxides and structureless detrital aggregates cemented by opal a barite and calcite occur around the main discharge conduits these aggregates are overlaid by silica carbonate fine layered stromatolitic aggregates that extend some meters from the hot springs forming crusts and coalescing rims over volcanic pebbles and boulders manganese crusts are made up of barium rich x ray amorphous todorokite like and romanechite phases and represent a rare example of a manganese deposit formed in a shallow submarine hydrothermal environment in the submarine diffuse venting area the hydrothermal precipitates are less conspicuous and consist in millimeter thick iron oxyhydroxide coatings on volcanic cobbles and boulders these coatings are composed of poorly crystallized six line ferrihydrite accompanied by minor cinnabar and fine grained colloform pyrite textures and fabrics of the mineral assemblages suggest microbial mediation for mineral deposition the vent precipitates display a significant enrichment of hg as and sb arsenic is probably adsorbed onto mn and fe oxide substrates the nasc north american shale composite normalized ree patterns of the vent precipitates show a pronounced positive eu anomaly that is probably inherited from the hydrothermal fluid

petrogenesis of picritic mare magmas constraints on the extent of early lunar differentiation calculations of isobaric batch polybaric batch and polybaric fractional melting have been carried out on a variety of proposed lunar and terrestrial source region compositions results show that magmas with a generally tholeiitic character plagioclase and high ca pyroxene crystallize before low ca pyroxene reflecting relatively high al2o3 concentrations 12 wt are the inevitable consequence of anhydrous partial melting of source regions composed primarily of olivine and two pyroxenes with an aluminous phase on the solidus low al2o3 magmas 10 wt as typified by the green picritic glasses in the lunar maria require deep 700 1000 km low al2o3 source regions without an aluminous phase the difference between primitive and depleted mantle beneath mid ocean ridges amounts to less than 0 1 wt al2o3 whereas formation of the green glass source region requires a net loss of between 1 5 and 2 5 wt al2o3 basalt extraction cannot account for fractionations of this magnitude accumulation of olivine and pyroxene at the base of a crystallizing magma ocean is however an effective method for producing the necessary al2o3 depletions both olivine rich and pyroxene rich source regions can produce the picritic magmas but mixing calculations show that both types of source region are likely to be hybrids consisting of an early to intermediate stage cumulate olivine plus enstatite and a later stage cumulate assemblage mass balance calculations show that refractory element enriched bulk moon compositions contain too much al2o3 to allow for the deep low al2o3 source regions even after extraction of an al2o3 rich 26 30 wt crust between 50 and 70 km thick

long chain alkenones in the early pliocene sicilian sediments trubi formation punta di maiata section implications for the alkenone paleothermometry abstract article history received 6 september 2010received in revised form 15 march 2011accepted 16 march 2011available online 23 march 2011keywords alkenoneearly pliocenereticulofenestridsmediterranean seasea surface temperature the u k 37 record and coccolithophorid remains in sediments from the early pliocene sicilian trubi formation punta di maiata have been estimated to assess the possible in uence of changes in the alkenone producingcoccolithophoridsontheu k 37 temperaturerelationship thesamplesweredominatedbysmallreticulofenestra r minutaandr minutula andthec 37 andc 38 methylandethylunsaturationratios u k 37 u k38me andu k38et weresimilar to those found in modern populations e huxleyi and g oceanica those results suggest that the earlypliocene small reticulofenetrids had a similar temperature sensitivity of u k 37 to thatfound in present day theseresults support the application of the u k 37 modern calibrations to reconstruct sst at least back in the pliocene 2011 published by elsevier b v

formation and evolution of a lunar core from ilmenite rich magma ocean cumulates abstract in the absence of comprehensive seismic data coverage the size composition and physical state of the lunar core are still debated it has been suggested that a dense ilmenite rich layer which originally crystallised near the top of the lunar magma ocean may have sunk to the centre of the moon to form either an outer core surrounding a small metallic inner core or a complete core if the lunar metallic iron content is insignificant here we study the formation gravitational stability and thermal evolution of both an ilmenite rich outer core and a full ilmenite rich core using a two dimensional cylindrical thermo chemical convection model gravity acceleration in the lunar mantle decreases quickly with depth since the gravity acceleration directly influences the buoyancy of materials the low gravity acceleration near the centre was explicitly taken into account core formation and evolution were investigated by assessing the effects of varying two parameters the mg density and the internal heat production of the ilmenite rich layer varying these parameters changes the compositional and thermal buoyancy of the dense layer models show that a stable ilmenite rich outer core may indeed have formed in the lunar interior and that its density depends on the internal heating in and the mg of the ilmenite rich layer furthermore the sharpness of the core mantle boundary is shown to depend on the internal heat production in the ilmenite rich material surprisingly a higher internal heat production results in a sharper core mantle boundary and a higher ilmenite content in the core this is caused by lower viscosities as a result of higher temperatures although maximum core temperatures vary between different models by 700 1000 k around 2 gyr after the start of the models present day estimates vary by only about 350 500 k further narrowing of the range of internal heating values is essential for a better determination of both the present day lunar core temperature and its physical state

the physical mechanisms of deep moonquakes and intermediate depth earthquakes how similar and how different abstract we here review the characteristics of deep moonquakes dmq and conclude that they share many common features with certain categories of intermediate depth earthquakes namely the pressure temperature conditions where they occur their occurrence in highly localized nests their tendency to occur repeatedly at the same or nearly the same location and their distribution of sizes b values we thus explore various physical mechanisms proposed for earthquakes that might also explain deep moonquakes these include the possibility that there are partial melts or fluid phases in the lunar mantle that permit dmq to occur at pressures where ordinary brittle fracture is not possible the possibility that stress concentration increases tidal stresses at certain locations where moonquakes occur repeatedly and the possibility that dmq occur at relatively low stresses because rock strength is lowered by a fatigue process induced by the repetitive application of tidal stresses the similarities between dmq and terrestrial earthquakes imply that research focusing on the properties of both phenomena may help us understand the physical origins of both

controls of fluid chemistry and complexation on rare earth element contents of anhydrite from the pacmanus subseafloor hydrothermal system manus basin papua new guinea ocean drilling program odp leg 193 successfully drilled four deep holes 126 to 386 m into basement underlying the active dacite hosted pacmanus hydrothermal field in the eastern manus basin anhydrite is abundant in the drill core material filling veins and vesicles cementing breccias and occasionally replacing igneous material we report rare earth element ree contents of anhydrite from a site of diffuse venting site 1188 which show extreme variability in terms of both absolute concentrations e g 0 08 28 3 ppm nd and pattern shape lan smn 0 08 3 78 smn ybn 0 48 23 1 eu eu 0 59 6 1 the range of ree patterns in anhydrite includes enrichments in the middle and heavy rees and variable eu anomalies the patterns differ markedly from those of anhydrite recovered during odp leg 158 from the tag hydrothermal system at the mid atlantic ridge which display uniform lree enriched patterns with positive eu anomalies very similar to tag vent fluid patterns as the system is active the host rock composition is uniform and the anhydrite veins appear to relate to the same hydrothermal stage we can rule out predominant host rock and transport control instead we propose that the variation in ree content reflects waxing and waning input of magmatic volatiles hf so2 and variable complexation of rees in the fluids ree speciation calculations suggest that increased fluoride and possibly sulfate concentrations at pacmanus may affect ree complexation in fluids whereas at tag only chloride and hydroxide complexes play a significant role the majority of the anhydrites do not show positive eu anomalies suggesting that the fluids were more oxidizing than in typical mid ocean ridge hydrothermal systems we use other hydrothermal fluids from the manus basin vienna woods and desmos which bracket the pacmanus fluids in terms of acidity and ligand concentrations to examine the dependence of ree complexation on fluid composition geochemical modeling reveals that under the prevailing conditions at pacmanus ph 3 5 t 250 300 c eu oxidation state and the relative importance of fluoride versus chloride complexing are very sensitive to small variations in oxygen fugacity temperature and ph patterns with extreme mid ree enrichment may reflect speciation effects free ion abundance coupled with crystal chemical control we conclude that the great variability in ree concentrations and pattern shape is likely due to variable fluid composition and ree complexation in the fluids

rare earth element abundances and distribution patterns in hydrothermally altered basalts experimental results oceanic tholeiites that have been experimentally reacted with seawater at 500 600 c 800 1000 bars have rare earth element ree abundances and distribution patterns that are essentially identical to those of the unaltered basalts although the data indicate the possibility of some ree leaching and redistribution the net effects are small and the ree patterns of basalts affected by submarine hydrothermal processes may still be valid petrogenetic indicators

the age of the miocene pliocene boundary in the capo rossello area sicily detailed correlations of magnetostratigraphy biostratigraphy and lithostratigraphy reveal that the basal pliocene is equally complete in the eraclea minoa and capo rossello sections sicily and the singa section calabria and that in accordance with the model of the pliocene flooding event in the mediterranean the deposition of the pelagic marls of the trubi formation started synchronously on sicily and in adjacent calabria in addition the data obtained from the trubi in the eraclea minoa section allows the age of the miocene pliocene boundary to be adjusted slightly from 4 83 4 84 1 to 4 86 ma because downward extrapolation of both sedimentation rate and average duration of small scale sedimentary cycles in the trubi yields this age for the boundary in this section linearly interpolated ages for the top of the sphaeroidinellopsis acme and the first substantial increase in globorotalia margaritae the fod of this species is non existent in the mediterranean pliocene at eraclea minoa arrive at 4 74 and 4 63 ma respectively because of the detailed magnetostratigraphy and the very accurate dating of the miocene pliocene boundary it is preferable to select the eraclea minoa section as the boundary stratotype rather than the capo rossello section finally this age of 4 86 ma for the miocene pliocene boundary suggests that the beginning of the pliocene is connected with the termination of a series of latest miocene glaciations and that the re establishment of open marine conditions in the mediterranean might be of glacio eustatic origin

new radiometric dating of volcanic ash layers in periadriatic foredeep basin system italy abstract new geochronological data are reported for two key ash beds interbedded in upper miocene messinian early pleistocene rocks at maccarone bellante and mosciano s angelo on the adriatic side of the italian peninsula major element chemistry of glass shards was determined with electron microprobe analysis on the younger key bed the older messinian age ash bed sampled at maccarone yields a corrected glass fission track age of 5 38 0 42 ma the younger ash bed sampled at mosciano s angelo and at two localities at bellante yields corrected glass ages of 2 1 ma similar to ages previously determined on pliocene pleistocene ash collected along the ionic coast and on the tyrrhenian side of italy apatite fission track dating of one of the bellante samples confirms the glass age whereas apatite from the mosciano s angelo sample yields an excessively old age due to the presence in the sample of a significant component of detrital grains an unusual bimodal spontaneous track diameter distribution is found in the maccarone glass similar to the distributions previously obtained on other messinian age tephra samples from the same region this anomalous track diameter distribution is interpreted as a thermal disturbance coeval with the volcanic activity that produced the pliocene pleistocene key volcanic ash bed sampled at bellante and mosciano s angelo the contemporaneity of this ash with the event detected by the maccarone glass suggests that it was related to the tectonic phase which marked with numerous erosive levels distributed along the whole apennine region the end of the pliocene sedimentary cycle and the onset of the pleistocene cycle

a three component model for the bulk composition of the moon abstract using detailed analyses of lunar pristine glasses as a basis delano 1986 we present a suite of models of lunar bulk composition which are based on the following assumptions i that the early moon differentiated into two primary reservoirs 1 an feo rich magma ocean and 2 an olivine rich residuum of fo90 and ii that this magma ocean then differentiated into an olivine dominated cumulate fo80 and a primitive liquid composition ppg thus in these models the bulk composition of the moon is given by a mixture of three components an early olivine residuum a later olivine orthopyroxene cumulate and ppg liquid with the constraint that the moon possess a ci chondritic mg al ratio our model lunar compositions are grossly similar to the lunar composition of ringwood et al 1987 and when projected from feo they appear very similar to the composition of the earth s upper mantle again when projected from feo our model magma ocean compositions are very similar to the bulk lunar composition derived by taylor 1982 remelting of cumulates from the magma ocean can produce the mare basalts and the pristine glasses remelting of the early residuum may be the source of the highly magnesian olivines found in the lunar highlands our ability to relate such diverse chemistries as the earth s mantle and taylor s moon is relatively model independent the model compositions discussed above are generated by assuming that the cumulate formed by equilibrium crystallization to better determine if there is a significant difference between the feo contents of the earth and the moon we have also calculated bulk lunar compositions whose cumulate component is formed by fractional crystallization a more realistic approximation we find that if the mg si ratios of the earth and moon are similar and if the early residue is dominated by olivine then the bulk silicate moon is 25 to 50 enriched in feo over the earth s upper mantle 10 to 13 wt feo for the moon as compared to 8 wt for the earth again the ultimate basis for this estimate of lunar feo is the set of lunar pristine glasses a characteristic of all our models is that refractory lithophile elements such as ca and al are calculated to be 2 to 3 times ci in the bulk silicate moon these abundances are largely determined by our requirement that the moon possess a chondritic mg al ratio to emphasize this point we discuss the implications of the choices of various mg al and mg si ratios in the calculation of bulk planetary compositions

age of the plio pleistocene boundary in the vrica section southern italy new palaeomagnetic data from the proposed plio pleistocene boundary stratotype section vrica section southern italy are presented here in order to improve the correlation of these sediments to the magnetic polarity time scale if the interpretation preferred here is correct the boundary falls above the olduvai normal subchron at approximately 1 6 myr

europium redox equilibria in aqueous solution thermochemical data and recent advances in theoretical aqueous solution chemistry enable prediction of the relative stabilities of aqueous eu2 and eu3 over a wide range of temperatures and pressures at low temperatures near earth surface conditions the aqueous geochemistry of europium should be dominated by the trivalent state except possibly in the most reducing alkaline pore waters of anoxic marine sediments however at temperatures greater than about 250 c and elevated pressures divalent europium should predominate even with significant amounts of complexing trivalent europium is not stable at elevated temperatures and pressures consequently under most hydrothermal and metamorphic conditions europium in aqueous solution should be divalent at intermediate temperatures around 100 c significant activities of both eu2 and eu3 and related complexes can occur in aqueous solutions depending on the oxidation state and the ph of the solutions and the activities of potential ligands such as sulfate carbonate and chloride the predicted stability of divalent europium in aqueous solution at elevated temperatures is consistent with the large positive europium anomalies in rare earth element patterns of high temperature barites of hydrothermal and metamorphic origin reported by guichard et al 5 and with the observed depletion of europium as a result of high temperature sericitization of feldspar bearing assemblages discovered by alderton et al 1 it is suggested that significant fractionation of europium relative to the other rare earth elements may take place during high temperature hydrothermal alteration processes such as in the mid oceanic ridge systems because of the expected stability of divalent europium during these processes

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

an overview of the post messinian paleoenvironmental history of the western mediterranean a review of the pliocene pleistocene paleoenvironmental history of the western mediterranean is presented based on micropaleontological and geochemical studies of ocean drilling program odp leg 107 material and marine outcrops in southern italy the calcareous plankton biochronology proposed for the mediterranean by rio et al 1990 and 1991a provides the necessary age control for determining the timing of major climatic and oceanographic changes in the region the early pliocene period in the mediterranean was not a time of warm stable climate rather it was marked by relatively high amplitude climatic oscillations in marginal areas these climatic oscillations resulted in the rhythmic deposition of limestone marl couplets which have an average duration of approximately 19 000 years it is proposed that these sedimentary couplets are the result of precessionally induced changes in monsoon intensity which in turn cause variability in coastal divergence and upwelling the 18o and the calcareous plankton foraminifera and coccoliths records for tyrrhenian sea odp site 653 reveal a cooling of surface waters at 3 1 ma coincident with this cooling is an increase in the frequency of diatomite formation in southern italy bianco section the global cooling at 2 4 ma and the associated expansion of northern hemisphere glaciation resulted in a shift to more arid conditions in the mediterranean region this climate change may have altered the mediterranean water balance resulting in the establishment of antiestuarine water exchange with the atlantic at this time the 18o record for site 653 is also marked by a sharp cooling across the pliocene pleistocene boundary in the boundary stratotype section at vrica this cooling is manifested as an increase in the abundance of the planktonic foraminifer neogloboquadrina pachyderma

calcareous plankton biostratigraphy and biochronology of the pliocene lower pleistocene succession of the capo rossello area sicily abstract in the first part of this paper we present the calcareous nannofossil biostratigraphy of the capo rossello section sicily which suggests that a sedimentary gap exists at the contact between the trubi and the overlying monte narbone formation close to the top of the proposed zanclean stratotype this suggestion is supported by the planktonic foraminiferal results and field observations in contrast the transition from the trubi to the monte narbone formation is well exposed gradational and biostratigraphically continuous in the nearby section of punta piccola a composite of the capo rossello and punta piccola sections serves as a good biostratigraphic reference for the pliocene of the mediterranean in a second part of this paper we have attempted to update the mediterranean pliocene time framework by integrating all of the available biostratigraphic biochronologic chronostratigraphic paleomagnetic and radiometric data

the rossello composite a mediterranean and global reference section for the early to early late pliocene a high resolution magnetostratigraphy planktonic foraminiferal biostratigraphy and cyclostratigraphy is presented for the pliocene trubi marls in the punta di maiata section on sicily the integrated stratigraphy of the rossello composite section of hilgen 1 newslett stratigr 17 1987 is thereby completed this composite section provides an unprecedented high quality reference section for the early to early late pliocene containing a continuous sequence ranging from below the thvera subchron into the matuyama chron 4 86 2 45 ma the punta di maiata section extends from the sidufjall subchron of the gilbert into the gauss chron 4 50 3 30 ma linear interpolation between paleomagnetic datum planes in this section yields first order age estimates of 3 72 0 01 and 3 59 0 01 ma for the last common occurrence lco and the actual last occurrence lo of globorotalia margaritae in addition this age of 3 59 ma provides an accurate age for the zanclean piacenzian z p boundary provided the lo of g margaritae is maintained as a criterion to define this boundary in the mediterranean irrespective however of the criterion used the punta di maiata and punta piccola subsections of the rossello composite are at present the most suitable sections to be designated as stratotypes for the z p boundary the global significance of the rossello composite is further strongly enhanced by the establishment of an astronomically calibrated geomagnetic polarity time scale based on the correlation of the trubi sedimentary cycles with the astronomical record

rare earth element geochemistry of the woxi w sb au deposit hunan province south china the woxi w sb au deposit in hunan south china is hosted by proterozoic metasedimentary rocks a turbiditic sequence of slightly metamorphosed greenschist facies gray green and purplish red graywacke siltstone sandy slate and slate the mineralization occurs predominantly 70 as stratabound stratiform ore layers and subordinately as stringer stockworks the former consists of rhythmically interbedded banded to finely laminated stibnite scheelite quartz pyrite and silty clays whereas the latter occurs immediately beneath the stratabound ore layers and is characterized by numerous quartz pyrite gold scheelite stringer veins or veinlets that are typically either subparallel or subvertical to the overlying stratabound ore layers the deposit has been the subject of continued debate in regard to its genesis rare earth element geochemistry is used here to support a sedimentary exhalative sedex origin for the woxi deposit the ree signatures of the metasedimentary rocks and associated ores from the woxi w sb au deposit remained unchanged during post depositional processes and were mainly controlled by their provenance the original ore forming hydrothermal fluids as demonstrated by fluid inclusions in quartz from the banded ores are characterized by variable total ree concentrations 3 5 to 136 ppm marked lree enrichment lan ybn 28 248 lree hree 16 to 34 and no significant eu anomalies eu eu 0 83 to 1 18 they were most probably derived from evolved seawater that circulated in the clastic sediment pile and subsequently erupted on the seafloor the bulk banded ores are enriched in hree lan ybn 4 6 11 4 lree hree 3 to 14 and slightly depleted in eu eu eu 0 63 to 1 14 relative to their parent fluids this is interpreted as indicating the influence of seawater rather than a crystallographic control on ree content of the ores within a single ore layer the degree of hree enrichment tends to increase upward while the total ree concentrations decrease reflecting greater influence and dilution of seawater there is a broad similarity in chondrite normalized ree patterns and the amount of ree fractionation of the bandedoresinthisstudyandexhalitesfromothersedex typepolymetallicoredeposits suggestingasimilargenesisforthesedeposits

rare earth element study of exhalites within the willyama supergroup broken hill block australia a wide variety of unusual rock types exhalites are commonly associated with or host to exhalative mineralisation within the willyama supergroup chondrite normalised ree patterns of feldspar gahnite calcite magnetite and garnet rich lithologies in the vicinity of stratiform broken hill type pb zn ag mineralisation are lree and eu enriched similar to the ree patterns of pure metalliferous sediments and hydrothermal fluids of the east pacific rise and the red sea in contrast tourmaline garnet amphibole feldspar and gahnite rich exhalites in strike extension of broken hill type orebodies possess lree enrichments and negative eu anomalies and also hree enrichments and negative ce anomalies these ree patterns are the result of decreasing temperatures of the hydrothermal fluids changing oxidation reduction conditions and increasing influence of basic volcanism with increasing distance from the sulphide mineralisation

rare earth element patterns in archean high grade metasediments and their tectonic significance abstract metasediments from two contrasting types of archean high grade terrains are interpreted as being derived from distinct tectonic settings the kapuskasing structural zone canada represents the deep roots of a typical greenstone belt whereas the limpopo province southern africa and western gneiss terrain australia mainly consist of shelf sediments deposited on a granitic basement and then buried to the depths required for granulite fades metamorphism upper amphibolite to granulite fades paragneisses from the kapuskasing structural zone have ree patterns similar to those of greenstone belt sediments except where partial melting has occurred forming restites with eu enrichment and melts with eu depletion except in this latter instance metamorphism has not affected the primary ree patterns ree patterns in archean upper amphibolite to granulite facies metasediments from the central limpopo province and western gneiss terrain show wide differences ranging from patterns which resemble those in post archean terrigenous sediments to typical archean sedimentary rock patterns the diversity in ree patterns for these shallow shelf metasediments is interpreted as resulting from derivation from local provenances samples with post archean patterns displaying eu depletion are interpreted as being derived from k rich granitic plutons which were portions of small stable early archean terrains precursors of the widespread late archean proterozoic episode of major cratonic development

thermodynamic properties of fe s alloys from molecular dynamics modeling implications for the lunar fluid core abstract density and sound velocity of fe s liquids for the p t parameters of the lunar core have not been constrained well from the analysis of seismic wave travel time weber et al 2011 proposed that the lunar core is composed of iron alloyed with 6 wt of light elements such as s a controversial issue in models of planetary core composition concerns whether fe s liquids under high pressure temperature conditions provide sound velocity and density data which match the seismic model here we report the results of molecular dynamics md simulations of iron sulfur alloys based on embedded atom model eam the results of calculations include caloric thermal and elastic properties of fe s alloys at concentrations of sulfur 0 18 at temperatures up to 2500 k and pressures up to 14 gpa the effect of sulfur on the elastic properties of fe rich melts is most evident in the notably decreased density with added s content in the md simulation the density and bulk modulus k t of liquid fe s decrease with increasing sulfur content while the bulk modulus k s decreases as a whole but has some fluctuations with increasing sulfur content the sound velocity increases with increasing pressure but depends weakly on temperature and the concentration of sulfur for a fluid fe s core of the moon 5 gpa 2000 k with 6 16 at s 3 5 10 wt the sound velocity and density may be estimated at the level of 4000 m s 1 and 6 25 7 0 g cm 3 comparison of thermodynamic calculations with the results of interpretation of seismic observations shows good agreement of p wave velocities in the liquid outer core while the core density does not match the seismic models at such concentrations of sulfur and a density by 20 35 higher than the model seismic density a radius for the fluid outer core should be less than about 330 km found by weber et al because at the specified mass and moment of inertia values of the moon an increase of the core density leads to a decrease of the core radius these results are important for modeling the current state and composition of the lunar core and can be applied to models of large satellites core properties

the ree content of some hydrothermal fluids ree concentrations were determined in solutions from submarine hydrothermal vents on the east pacific rise and for the first time from continental geothermal fields in tibet and bulgaria they indicate that in hydrothermal systems ree are immobile at temperatures below 350 c and for water rock ratios of 105 nd values of submarine solutions and anhydrites 4 7 to 6 2 suggests recharge on the sedimentcovered flanks of the ridge carbonate anions as measured by alkalinity appear to increase the solubility of heavy ree somewhat but not to the extent that substantial amounts of ree could be driven out from rocks by hydrothermal activity

hydrothermal nontronite formation associated with microbes from low temperature diffuse hydrothermal vents at the south mid atlantic ridge oceanic nontronite deposits have been identified to be closely related to low temperature hydrothermal activities however their formation mechanisms associated with microbes in diffuse hydrothermal vents still remain largely unknown the friable deposits collected from the low temperature diffuse flow at the southern atlantic ridge display a layered structure scanning electron microscope sem and transmission electron microscope tem analyses reveal that abundant filamentous spherical and rod shaped mineralized forms are preserved in the yellowish green layer of the deposits these mineralized forms primarily consist of si and fe selected area electron diffraction saed patterns of the mineralized forms indicate that they are composed of nontronite high intensities of 12c and 12c14n signals derived from cellular structures determined by nano secondary ion mass spectrometry nanosims suggest the intimate relationship between nontronite and microbes the results of 454 pyrosequencing analyses provide insights into the microbial communities involved in the biologically induced mineralization in the yellowish green layer we propose an evolutionary model for establishing paragenetic sequences among nontronite mn oxide and fe oxyhydroxide in the deposits this paragenetic sequence could be widespread in modern and ancient low temperature hydrothermal fields

geophysical constraints on lunar bulk composition and structure a reassessment theoretical lunar mantle seismic velocity and density profiles are calculated for a series of proposed bulk compositions present day selenotherms and models for early differentiation and evolution the seismic velocity profiles are compared to the most recent observational model derived from the complete apollo data set to evaluate compositional implications the mantle density profiles are compared to mean density moment of inertia and crustal density thickness constraints to evaluate the need for a metallic core the calculated seismic velocity profiles are in qualitative agreement with the observational model in two general respects 1 a quasicontinuous velocity decrease occurs in the upper mantle due to the large thermal gradients that characterize all three of the considered thermal models 2 a discontinuous velocity increase occurs at the spinel to garnet transition approximately 500 km depth due mainly to the higher garnet velocities as compared to olivine and orthopyroxene in the upper mantle all four of the considered bulk compositions spanning a range of plausible feo and al2o3 contents are allowed when uncertainties in the temperature profile and depth of differentiation are taken into account however in the middle mantle depths 500 km the most aluminous models those with larger garnet abundances consistently produce larger velocity increases that are most nearly in accord with the observational model in general models that assume differentiation of the upper mantle only that are more aluminous in bulk composition and that have strong thermal gradients in the upper mantle but smaller gradients in the middle mantle result in calculated velocity profiles that most nearly agree with the observational velocity model an alternate differentiation model in which the middle mantle is dominated by mgo rich mafic silicates is also in accord with the observational seismic velocity model but results in density decreases that appear to violate stability arguments in every case calculated mantle density increases are insufficient to match the one standard deviation upper limit on the moment of inertia even when the most favorable combinations of allowed crustal thickness and density are assumed agreement with the moment of inertia upper limit is obtained if metallic cores representing 1 4 of the lunar mass are added to the bulk composition such cores are larger than needed to explain the observed depletions of lunar siderophile elements if the moon formed entirely from terrestrial mantle material

rare earth element mobility in alteration pipes below massive cuzn sulfide deposits abstract a convincing demonstration of trace element mobility should satisfy two criteria 1 the range of trace element concentrations in the rock before and after alteration must be known with confidence and 2 the absolute abundances and the ratios of the mobile trace elements should vary between altered and unaltered rocks these criteria have been applied to the host felsic volcanics and alteration pipes associated with several canadian massive cu zn sulfide deposits although there is no evidence of rare earth element ree mobility in the pervasive low grade alteration envelopes adjacent to the deposits the light and middle ree lree and mree plus y have been systematically mobilized relative to the heavy ree hree and other trace elements in the alteration pipes beneath the ore zones there is evidence of minor lree and mree depletion in the most altered rocks at the south bay mine uchi lake and of significant lree depletion in the alteration pipe beneath the mattabi mine sturgeon lake however the strongest mobility is found at the kidd creek mine where the lree were leached from the rocks in the footwall stringer zone and redeposited in a metasomatic chlorite zone directly beneath the massive ore horizon and the mree and y were preferentially lost from the system producing distinctive chondrite normalized ree patterns with tb yb n ratios less than unity eu2 was found to be more mobile than the trivalent ree especially at kidd creek where there is a marked increase in the magnitude of the eu anomaly in the most altered samples high field strength elements such as u th hf and zr have not decoupled and apparently remained relatively immobile during all but the most intense alteration i e kidd creek preliminary data suggest that the degree of ree mobility increases with the size of the deposit thus ree mobility is a potentially useful method of distinguishing between small and large massive sulfide deposits at an early stage in exploration however this hypothesis requires further testing

rare earth elements and hydrothermal ore formation processes abstract the geochemical behaviour of ree is influenced by nearly all important hydrothermal ore formation processes including fluid rock interactions fluid precipitations adsorption and scavenging onto particles and changes in fluid temperature pressure ph eh alkalinity and ligand concentration destabilization of ree complexes in response to these physicochemical changes and possible chemical crystallographic controls determine the concentration and distribution of ree within hydrothermal minerals mineraloids and amorphous phases alteration assemblages of intrusive related mineralisations may exhibit a wide range of ree distributions and ree fractionation trends the ree distribution within these hydrothermally altered lithologies will depend on the ree concentration in the rock and the fluid the partitioning behaviour of the ree between the rock phases and the fluid and the types of alteration reactions which take place reactive rocks such as carbonate rich lithologies of skarn deposits may gain or loose significant amounts of ree during fluid rock interactions ree geochemical investigations combined with fluid inclusion and stable isotope studies may point to the origin of alteration products and the source s of ore fluids ancient massive sulphide ores commonly exhibit anomalous eu concentrations similar to many recent submarine hydrothermal precipitates the recognition of hydrothermal fluid seawater sedimentary or volcanically derived ree distributions within ores chemical sediments and hydrothermally altered lithologies may help to constrain genetic modelling of massive sulphide deposits care should be taken with the interpretation of ree distributions from metamorphosed hydrothermal ore deposits becase metamorphic and diagenetic alteration reactions may change the ree distributions mobility of ree may occur during diagenesis of carbonate rich rocks and during the development of shear zones and migmatites in contrast very large fluid rock ratios are necessary to cause significant changes in ree patterns of silicate rich rocks during diagenesis and regional metamorphism

seismic velocity structure of the lunar mantle i have inverted the recently completed set of seismic arrival times from the apollo lunar seismic network to estimate the average seismic velocities in three sections of the lunar mantle two for the upper mantle and one for the middle mantle the method used is a variation of the linearized least squares inversion where the inversion is accomplished in steps the estimated average velocities in the upper mantle decrease from vp 7 74 km s and vs 4 49 km s in the section above 270 km depth to vp 7 46 km s and vs 4 25 km s in the section between 270 and 500 km depth confirming the earlier finding of negative gradients based on seismic amplitude variations the average velocities in the middle mantle between the depths of 500 km and 1000 km of vp 8 26 km s and vs 4 65 km s are significantly higher than those in the upper mantle contradicting earlier estimates based on more limited data the higher velocities may suggest initial melting of the moon down to at least 1000 km depth