crystals stirred up 1 direct numerical simulations of crystal settling in nondilute magmatic suspensions 1 this is the first paper in a two part series examining the fluid dynamics of crystal settling and flotation in the lunar magma ocean a key challenge in constraining solidification processes is determining the ability of individual crystals to decouple from vigorous thermal convection and settle out or float the goal of this paper is to develop a computational methodology capable of capturing the complex solid fluid interactions that determine settling and flotation in the second paper we use this computational approach to explore the conditions under which plagioclase feldspar would be able to buoyantly float and form the earliest crust on the moon the direct numerical method described in this paper relies on a fictitious domain approach and captures solid body motion in 2d and 3d with little overhead beyond single fluid calculations the two main innovations of our numerical implementation of a fictitious domain approach are an analytical quadrature scheme which increases accuracy and reduces computational expense and the derivation of a multibody collision scheme advantages of this approach over previous simulations of crystal bearing magmatic suspensions include the following 1 we fully resolve the two way interaction between fluid and solid phases implying that crystals are not only passively advected in an ambient flow field but are also actively driving flow and 2 we resolve the flow around each individual crystal without assuming specific settling speeds or drag coefficients we present several benchmark problems and convergence tests to validate our approach

formation and age of sphalerite mineralization in carbonate rocks of bajocian age in the swiss jura mountains evidence of mesozoic hydrothermal activity a combination of petrographic and geochemical techniques was applied to better constrain the origin and evolution of the fluid systems responsible for the formation of disseminated cd rich up to 0 6 wt sphalerite zns mineralization in the northeastern part of the jura mountains switzerland the rb sr ages of sphalerite samples indicate that a main phase of sphalerite formation occurred near the boundary between the late middle and early late jurassic at around 162 ma the negative 34s values 22 3 to 5 3 suggest that biogenic sulfide sulfur was involved in zns precipitation the strontium isotope composition is more radiogenic than that of contemporaneous seawater reflecting the interaction of mineralizing fluids with silicate rocks lead isotope signatures are very uniform 206pb 204pb 18 63 18 67 207pb 204pb 15 63 15 64 208pb 204pb 38 51 38 63 indicating an isotopically well homogenized fluid system the basement rocks underlying the jurassic strata are considered to be the main source of metals for the sphalerite mineralization the migration of deep sourced hydrothermal saline metal bearing fluids into the bajocian host carbonates containing sedimentary reduced sulfur resulted in the precipitation of sulfides the period of sphalerite formation near the middle late jurassic boundary is characterized by enhanced tectonic and hydrothermal activity in europe related to the opening of the central atlantic and tectonic thermal subsidence during spreading of the alpine tethys our study provides evidence that the bajocian carbonate rocks in the jura mountains area were affected by the circulation of deep sourced metal bearing hydrothermal fluids in response to these continent wide tectonothermal events the presence of sphalerite mineralization and associated geochemical anomalies in zn and cd contents in carbonate rocks may also be used to trace basement features

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

quantitative zn speciation in a contaminated dredged sediment by μ pixe μ sxrf exafs spectroscopy and principal component analysis dredging and disposal of sediments onto agricultural soils is a common practice in industrial and urban areas that can be hazardous to the environment when the sediments contain heavy metals this chemical hazard can be assessed by evaluating the mobility and speciation of metals after sediment deposition in this study the speciation of zn in the coarse 500 to 2000 m and fine 2 m fractions of a contaminated sediment dredged from a ship canal in northern france and deposited on an agricultural soil was determined by physical analytical techniques on raw and chemically treated samples zn partitioning between coexisting mineral phases and its chemical associations were first determined by micro particle induced x ray emission and micro synchrotron based x ray radiation fluorescence zn containing mineral species were then identified by x ray diffraction and powder and polarized extended x ray absorption fine structure spectroscopy exafs the number nature and proportion of zn species were obtained by a coupled principal component analysis pca and least squares fitting lsf procedure applied herein for the first time to qualitatively number and nature of species and quantitatively relative proportion of species speciate a metal in a natural system the coarse fraction consists of slag grains originating from nearby zn smelters in this fraction zn is primarily present as sphalerite zns and to a lesser extent as willemite zn2sio4 zn containing ferric oxyhydr oxides and zincite zno in the fine fraction zns and zn containing fe oxyhydr oxides are the major forms and zn containing phyllosilicate is the minor species weathering of zns zn2sio4 and zno under oxidizing conditions after the sediment disposal accounts for the uptake of zn by fe oxyhydr oxides and phyllosilicates two geochemical processes can explain the retention of zn by secondary minerals uptake on preexisting minerals and precipitation with dissolved fe and si the second process likely occurs because dissolved zn and si are supersaturated with respect to zn phyllosilicate exafs spectroscopy in combination with pca and lsf is shown to be a meaningful approach to quantitatively determining the speciation of trace elements in sediments and soils

a model of the primordial lunar atmosphere abstract we create the first quantitative model for the early lunar atmosphere coupled with a magma ocean crystallization model immediately after formation the moon s surface was subject to a radiative environment that included contributions from the early sun a post impact earth that radiated like a mid type m dwarf star and a cooling global magma ocean this radiative environment resulted in a largely earth side atmosphere on the moon ranging from 104 to 102 pascals composed of heavy volatiles na and sio this atmosphere persisted through lid formation and was additionally characterized by supersonic winds that transported significant quantities of moderate volatiles and likely generated magma ocean waves the existence of this atmosphere may have influenced the distribution of some moderate volatiles and created temperature asymmetries which influenced ocean flow and cooling such asymmetries may characterize young tidally locked rocky bodies with global magma oceans and subject to intense irradiation

orographic clouds in terrain blocked flows an idealized modeling study abstract idealized numerical simulations of moist strongly stratified flow over topography are used to study the processes that control orographic clouds in terrain blocked flows as a joint function of the nondimensional flow parameter nh u the horizontal topographic aspect ratio and the rossby radius of deformation nh f the simulations show the competition between enhanced upstream condensation in the secondary vertically propagating gravity wave and the reduction of condensation owing to enhanced low level flow deflection as nh u increases above about 1 5 the tendency for flow to be deflected around the barrier reduces cloud formation in the primary gravity wave over the ridge while increasing expands low level clouds over a broader upstream area ice clouds may form aloft in the secondary vertically propagating gravity wave and extend upstream for several hundred kilometers in terrain blocked flows more than half of the condensate mass develops upstream of the barrier in the secondary gravi

a model for the thermal and chemical evolution of the moon s interior implications for the onset of mare volcanism crystallization of the lunar magma ocean creates a chemically stratified moon consisting of an anorthositic crust and magma ocean cumulates overlying the primitive lunar interior within the magma ocean cumulates the last liquids to crystallize form dense ilmenite rich cumulates that contain high concentrations of incompatible radioactive elements the underlying olivine orthopyroxene cumulates are also stratified with later crystallized denser more fe rich compositions at the top this paper explores the chemical and thermal consequences of an internal evolution model accounting for the possible role of these sources of chemical buoyancy rayleigh taylor instability causes the dense ilmenite rich cumulate layer and underlying fe rich cumulates to sink toward the center of the moon forming a dense lunar core after this overturn radioactive heating within the ilmenite rich cumulate core heats the overlying mantle causing it to melt in this model the source region for high tio2 mare basalts is a convectively mixed layer above the core mantle boundary which would contain small and variable amounts of admixed ilmenite and kreep this deep high pressure melting as required for the generation of mare basalts occurs after a reasonable time interval to explain the onset of mare basalt volcanism if the content of radioactive elements in the core and the chemical density gradients above the core are sufficiently high but within a range of values that might have been present in the moon regardless of details implied by particular model parameters gravitational overturn driven by the high density of magma ocean fe rich cumulates should concentrate high tio2 mare basalt sources and probably a significant fraction of radioactive heating toward the center of the moon this will have important implications for both the thermal evolution of the moon and for mare basalt genesis

autumnal precipitation distribution on the southern flank of the alps a numerical model study of the mechanisms during the autumn there are frequent events of heavy precipitation on the southern slopes of the meso scale alpine chain moreover the accompanying climatology exhibits a distinctive spatial distribution with some meso scale regions of enhanced precipitation such as the wet spot in the vicinity of lago maggiore possible mechanisms to account for the observed spatial distribution are established using a heuristic model based approach it is shown using a mesoscale model that the response to a steady horizontally uniform and moisture laden flow impinging upon a comparatively realistic representation of the alpine chain can reproduce both the overall meso scale precipitation distribution and its meso scale sub structure the nature of the simulated flow regime over around or intermediate is sensitive to the strength of the ambient geostrophic flow and its modification in the planetary boundary layer contrariwise the simulated precipitation distribution in the lago maggiore wet spot is comparatively insensitive to the changes in direction of the incident geostrophic flow from south to south west and in strength in the range 10 30 m s 1 although there is a marked change in the structure of the near alpine flow this systematic precipitation enhancement appears to be related to the relative strength and compensating effects of an easterly barrier jet tracking along the zonally elongated part of the alps and an air stream channelled between the maritime alps and the apennines further evidence to the above interpretation of the meso scale precipitation distribution is given with simulations conducted using a smoothed and schematic representation of the alpine chain likewise the sensitivity to the presence of a lago maggiore like indentation of the topography is tested and evidence is provided of a further indentation induced precipitation enhancement at the local scale copyright 2004 royal meteorological society

lunar core formation new constraints from metal silicate partitioning of siderophile elements abstract analyses of apollo era seismograms lunar laser ranging data and the lunar moment of inertia suggest the presence of a small at least partially molten fe rich metallic core in the moon but the chemical composition and formation conditions of this core are not well constrained here we assess whether pressure temperature conditions can be found at which the lunar silicate mantle equilibrated with a fe rich metallic liquid during core formation to this end we combine measurements of the metal silicate partitioning behavior of siderophile elements with the estimated depletion due to core formation in those elements in the silicate mantle of the moon we also explore how the presence of the light element sulfur suggested by seismic models to be present in the core at concentrations of up to 6 wt in the lunar core affects core formation models we use published metal silicate partitioning data for ni co w mo p v and cr in the lunar pressure range 1 atm 5 gpa and characterize the dependence of the metal silicate partition coefficients d on temperature pressure oxygen fugacity and composition of the silicate melt and the metal if the core is assumed to consist of pure iron core mantle equilibration conditions that best satisfy lunar mantle depletions of five siderophile elements ni co w mo and p are a pressure of 4 5 0 5 gpa and a temperature of 2200 k the lunar mantle depletions of cr and v are also consistent with metal silicate equilibration in this pressure and temperature range if 6 wt s is incorporated into the lunar core our results therefore suggest that metal silicate equilibrium during lunar core formation occurred at depths close to the present day lunar core mantle boundary this provides independent support for both the existence of a deep magma ocean in the moon in its early history and the presence of significant amounts of sulfur in the lunar core

changes in zn speciation during soil formation from zn rich limestones in order to better understand the long term speciation and fractionation of zn in soils we investigated three soils naturally enriched in zn 237 864 mg kg zn from the weathering of zn rich limestones 40 207 mg kg zn using extended x ray absorption fine structure exafs spectroscopy and sequential extractions the analysis of bulk exafs spectra by linear combination fitting lcf indicated that zn in the oolitic limestones was mainly present as zn containing calcite at site dornach zn containing goethite gurnigel and zn containing goethite and sphalerite liestal correspondingly extraction of the powdered rocks with 1 m nh4 acetate at ph 6 0 mobilized only minor fractions of zn from the gurnigel and liestal limestones 30 but most zn from the dornach rock 81 in the dornach soil part of the zn released from the dissolving limestone was subsequently incorporated into pedogenic hydroxy interlayered vermiculite zn hiv 30 and zn containing kaolinite 30 and adsorbed or complexed by soil organic and inorganic components 40 the gurnigel and liestal soils contained substantial amounts of zn containing goethite 50 stemming from the parent rock smaller amounts 20 of zn containing kaolinite and possibly zn hiv as well as adsorbed or complexed zn species 30 in the soil from liestal sphalerite was only found in trace amounts indicating its dissolution during soil formation in sequential extractions large percentages of zn 55 85 were extracted in recalcitrant extraction steps confirming that zn hiv zn containing kaolinite and zn containing goethite are highly resistant to weathering these zn bearing phases thus represent long term hosts for zn in soils over thousands of years the capability of these phases to immobilize zn in heavily contaminated soils may however be limited by their uptake capacity especially hiv and kaolinite or their abundance in soil

crystals stirred up 2 numerical insights into the formation of the earliest crust on the moon 1 this is the second paper in a two part series examining the fluid dynamics of crystal settling and flotation in the lunar magma ocean in the first paper we develop a direct numerical method for resolving the hydrodynamic interactions between crystals and their feedback on the flow field in magmatic liquid in this paper we use this computational technique to test the leading model for the formation of the earliest crust on the moon the anorthositic lithology of the lunar crust is thought to have been formed by the flotation of buoyant plagioclase crystals at a time when the lunar mantle was still wholly or largely molten this model is appealing from an observational point of view but its fluid dynamical validity is not obvious because 1 plagioclase probably started crystallizing very late i e when the magma ocean was already 80 solidified and 2 a significant portion of the shallow lunar crust consists of almost pure plagioclase 90 vol requiring very efficient plagioclase segregation the goal of this study is to better understand the fluid dynamical conditions that hinder or facilitate crystal settling or flotation our approach complements earlier studies by explicitly linking the petrological and fluid dynamical evolution and by focusing on the effect of increasing crystal fraction we find that crystal settling was probably possible throughout the entire solidification history of the lunar magma ocean as long as crystal sizes were sufficiently large r 1 mm and crystal fraction sufficiently low 13

analysis and simulation of local and regional conditions for the rainfall over the lago maggiore target area during map iop 2b the mesoscale alpine programme map operational and research network collected a large variety of measurements during the two days of intensive observing period iop 2b 19 and 20 september 1999 which is one of the most intense rainfall episodes during the special observing period over the lago maggiore area the synoptic situation is a typical one of a southerly flow and associated convection over alpine orography simulations with the non hydrostatic meso nh model are used to describe the rainfall conditions and are successfully validated at the different scales allowed by the map data the two types of pre frontal orographically triggered convective episodes are described 1 sporadic and shallow convection occurs over the coastal mountains and propagates over the po valley the chronology and the intensity of these convective episodes are driven by two main features the low level humidity anomalies and the middle troposphere dry anomaly present over the mediterranean sea 2 the lago maggiore orographic convection has a very long duration and is mainly controlled by both the intensity of the easterly low level wind in the north part of the po valley and the upper level clouds of the cold front the different origins of the air masses transported by this easterly barrier wind and the associated local circulations are detailed copyright 2003 royal meteorological society

first principles calculations of equilibrium ca isotope fractionation implications for oldhamite formation and evolution of lunar magma ocean abstract calcium is a major element of the earth the moon terrestrial planets and rocky meteorites here we present equilibrium ca isotope fractionation factors of ca bearing minerals using the first principles calculations based on density functional theory dft the sequence of minerals from the isotopically heaviest to the lightest in ca is forsterite orthopyroxene opx grossular pigeonite diopside anorthite oldhamite overall the equilibrium fractionation of ca isotopes is mainly controlled by the average bond lengths although oldhamite is enriched in light ca isotopes relative to silicate minerals in equilibrium natural oldhamite of enstatite chondrites are isotopically heavier than coexisting silicate materials this implies that enstatite chondrites oldhamites should have been formed during solar nebular gas condensation instead than during parent body processing following previous models for crystallization of the lunar magma ocean lmo we simulated ca isotopic fractionation of the lmo based on our calculated equilibrium ca isotope fractionation factors it shows that the 44 40 ca of the lunar anorthositic crust should be lower than the average of the bulk moon by 0 09 0 11 considering that the lunar mantle might have overturned and mixed after solidification of the lmo we further predict that the lunar mantle should be isotopically heavier than the bulk moon by 0 17 0 26 if the mantle was fully overturned or only by 0 06 0 08 for the case of fully mixing therefore we predict that the potential offset of ca isotopic composition between the anorthositic crust and the lunar mantle can be used to test lmo evolution models

crystal settling in a vigorously converting magma chamber there has been much debate concerning the mechanism of fractional crystallization in magma chambers the traditional hypothesis of crystal settling has been widely replaced by the concept of in situ crystallization coupled with compositional convection observations from layered intrusions however are equivocal1 4 doubts have been raised about crystal settling on theoretical grounds because convective velocities in magma chambers are often much greater than the crystal settling velocities predicted by stokes law5 but there has been no experimental study of crystal settling in such vigorous convection here we present physical considerations and laboratory experiments which show that the phenomenon of particle settling in these conditions can be accounted for by a simple theory application of this theory to crystal settling in magma chambers suggests that crystal settling may be an efficient differentiation mechanism at least in basaltic magma chambers despite large convective velocities

thermodynamics of silicate liquids in the deep earth article i nfo we discuss the geophysical implications of recent first principles molecular dynamics simulations of mgsio3 liquid in particular the findings that the gruneisen parameter increases by a factor of three on two fold compression and the predicted melting curve the predicted melting temperature of mgsio3 perovskite at 136 gpa is 5400 600 k which if lowered by freezing point depression by 1300 k yields a mantle solidus temperature of 4100 k identical to recent estimates of the temperature at the base of the mantle we argue on this basis that partial melting at the base of the mantle is plausible while mgsio3 perovskite is denser than the isochemical liquid reasonable values of iron partitioning and bulk iron contents leads to the conclusion that a melt at the base of the multi component mantle would be denser than its surroundings and therefore buoyantly stable we predict the bulk sound velocity of this melt to be 10 9 km s 1 less than that of ultra low velocity zones and consistent with the explanation of these regions as being due to partial melting the increase on compression of the gruneisen parameter in the liquid state yields isentropes that are much hotter than previously thought a potential temperature of only 2450 k is sufficient to melt the entire mantle and a magma ocean will begin crystallization at mid mantle depths rather than at the base of the mantle

reactivated basement structures affecting the sedimentary facies in a tectonically quiescent epicontinental basin an example from nw switzerland abstract the jurassic deposits in the southern part of central europe accumulated in a shallow epicontinental sea and their deposition has usually been believed to have corresponded to a phase of tectonic quiescence neither on conventional seismic records nor in outcrops obvious indications of synsedimentary tectonics were found nonetheless subtle variations in lithofacies and thickness occur above faults in the crystalline basement in fact preexisting structures became reactivated in the jurassic during major extensional phases when the tethys and the north atlantic opened this reactivation led to differential subsidence and or to rotation of fault bounded blocks but the sediments were deformed mainly flexurally as vertical movements in the basement were dissipated by triassic salt thus the depositional area was morphologically differentiated into swells and depressions in siliciclastic muddy environments swells were characterized by hardbottoms and hiatus beds depressions were filled by distal tempestites and gravity deposits in carbonate settings reefs nucleated on swells marls and muds were deposited in depressions many of them gravity deposits reactivation of faults occurred only during short episodes and was not synchronous throughout the study area and reactivation of individual faults was episodic and probably controlled by the palaeostress field and the faults orientation reactivation of deep rooted faults is also documented by hydrothermal activity which led to vein mineralization and alteration of minerals today exposed in nearby basement units the chronostratigraphic ages of the hydrothermal processes coincide with phases of enhanced subsidence during the sinemurian aalenian bajocian bathonian and oxfordian in turn facies changes of the sedimentary cover should be useful to predict basement structures when no seismic records are available

upstream effects of mesoscale mountains abstract the alpine experiment alpex has revealed that low level air is typically diverted around the alps without reaching the mountaintop in pursuit of an understanding of the physical basis of this phenomenon and of its generality we have explored the characteristics of orographic blocking of a rotating continuously stratified quid as revealed in a simple model problem retaining full nonlinear and transient effects hydrostatic dynamics is assumed and the obstacle is taken to be an infinitely long ridge with height h x the key questions treated are the strength of the upstream deceleration of cross mountain flow and the length scale over which the decelerated region extends by means of scale analysis the controlling parameters are found to be the rossby number ro u fl and the froude number fr nhm u where u is the speed of the oncoming flow f is the coriolis parameter l the mountain half width n the brunt vaisala frequency and hm is the maximum mountain height the scale analysis also

physical state of the very early earth abstract the earliest surface environment of the earth is reconstructed in accordance with the planetary formation theory formation of an atmosphere is an inevitable consequence of earth s formation the atmosphere near the close of accretion is composed of 200 300 bars of h2 and h2o and several tens of bars of co and co2 either by the blanketing effect of the proto atmosphere or heating by large planetesimal impacts a magma ocean is formed during accretion we can distinguish three stages for the thermal evolution of the magma ocean and proto crust stage 0 is characterized by a super liquidus or completely molten regime near the surface at this stage the surface of the earth is covered by a super liquidus magma ocean no chemical differentiation is expected during this stage once the energy flux released by planet formation decreases to the 200 w m2 level the super liquidus magma ocean then disappears within a time interval of 1 m y this is the transition from stage 0 to 1 stage 1 is characterized by a partially molten magma ocean in the magma ocean consisting of 20 30 partial melt heat transport is controlled by melt solid separation a type of compositional convection rather than thermal convection chemical differentiation of the mantle mainly occurs in this stage once the energy flux drops to the 160 w m2 level more than 90 of water vapor in the proto atmosphere condense to form the proto oceans several tens of bars of co and co2 remain in the atmosphere just after formation of the oceans water oceans are occasionally evaporated by large impacts after each such event recondensation of the ocean takes several hundred years although the surface is covered by a chilled proto crust it is short lived because of extensive volcanic resurfacing activity as well as meteorite impacts resurfacing this stage ends when the energy flux drops to 0 1 1 w m2 level the duration time of stage 1 is estimated to be several hundred million years the best estimate is about 400 m y stage 2 is characterized by solid state convection this stage continues to the present day one of the most important change on the proto earth is the transition from stage 1 to 2 which occurs several hundred million years after the earth formation long lived crust is formed only after this transition

quantifying magma segregation in dykes abstract the dynamics of magma flow is highly affected by the presence of a crystalline load during magma ascent it has been demonstrated that crystal melt segregation constitutes a viable mechanism for magmatic differentiation moreover crystal melt segregation during magma transport has important implications not only in terms of magma rheology but also in terms of differentiation of the continental crust however the influences of the crystal volume percentage of their geometry their size and their density on crystal melt segregation are still not well constrained to address these issues we performed a parametric study using 2d direct numerical simulations which model the ascension of a crystal bearing magma in a vertical dyke using these models we have characterised the amount of segregation as a function of different physical properties including the density contrast between crystals and the melt phase the size of the crystals ac and their aspect ratio r results show that small values of r do not affect the segregation in this case the amount of segregation depends upon four parameters segregation is highest when and ac are large and lowest for large pressure gradient pd and or large values of dyke width wd these four parameters can be combined into a single one the snumber which can be used to quantify the amount of segregation occurring during magma ascent based on systematic numerical modelling and dimensional analysis we provide a first order scaling law which allows quantification of the segregation for an arbitrary snumber and encompassing a wide range of typical parameters encountered in terrestrial magmatic systems although developed in a simplified system this study has strong implications regarding our understanding of crystal segregation processes during magma transport our first order scaling law allows to immediately determine the amount of crystal melt segregation occurring in any given magmatic dyke system

flow over mountains coriolis force transient troughs and three dimensionality some issues concerning uniform stratified flow over a three dimensional mountain that have not been fully explored are studied using primitive equation models when the froude number fr is small e g fr 0 5 we find that the coriolis force cannot be neglected for flow over small scale mountains characteristic length l 50 km even though the rossby number ro is large when the coriolis force is neglected a pair of symmetric vortices is induced on the lee side irrespective of the scale of the mountain as long as fr lies roughly between 0 1 and 0 5 the major effect of the coriolis force is to modify or diminish the lee vortices due to the leftward deflection on the upstream side of the mountain the coriolis deflection also reduces the upstream propagation when fr is 1 most of the flow goes over the mountain and the coriolis effect is small for the same ro therefore the importance of the coriolis effect is determined by both ro and fr as the scale of the mountain increases from small scale to mesoscale 100 km l 300 km the upstream flow is deflected more to the left by the coriolis effect and a trough develops on the lee side the length scale of the trough depends on the scale of the mountain in the along flow direction for smaller scale mountains small vortices can be generated within the lee side trough when fr is small when the mountain scale is increased the lee side vortices disappear and only a lee side trough remains depending on the mean wind speed and the mountain scale the lee side trough can be advected by the anticyclonic flow over the mountain to the south and remain attached to the mountain for a long time a train of troughs is generated on the lee side of an elliptic mountain associated with the lee side gravity waves simulations of flows over mountains in two dimensional and three dimensional models with the same cross sectional profile are compared for small scale mountains l 100km the two dimensional model overestimates the amount of airflow over the mountain and also the lee side downslope wind

blocking and frontogenesis by two dimensional terrain in baroclinic flow part i numerical experiments the shallow atmospheric fronts that develop in the early winter along the east coast of north america have been attributed in various modeling and observational studies to the land sea contrasts in both surface heating and friction however typical synoptic conditions are such that these coastal fronts could also be a type of upstream influence by the appalachian mountain chain generalized models have suggested that relatively cold air can become trapped on the windward side of a mountain range during episodes of warm advection without a local contribution from differential surface fluxes such a process was proposed decades ago in a study of observations along the coast of norway could coastal frontogenesis be primarily a consequence of a mountain circulation acting on the large scale temperature gradient a two dimensional terrain following numerical model is used to find conditions under which orography may be sufficient to cause blocking and upstream frontogenesis in a baroclinic environment the idealized basic flow is taken to have constant vertical shear parallel to a topographic ridge and a constant perpendicular wind that advects warm or cold temperatures toward the ridge land sea contrasts are omitted in the observed cases the mountain is narrow in the sense that the rossby number is large this by itself increases the barrier effect but the experiments show that large scale warm advection is still crucial for blocking for realistic choices of ambient static stability and baroclinicity the flow can be blocked by a range like the northern appalachians if the undisturbed incident wind speed is around 10 m s21 cold advection weakens the barrier effect the long term behavior of the front in strongly blocked cases is described and compared to observations because of the background rotation and large scale temperature advection blocked solutions cannot become steady in the assumed environment however the interface between blocked and unblocked fluid can settle into a balanced configuration in some cases a simple argument suggests that in the absence of dissipation the frontal slope should be similar to that of the ambient absolute momentum surfaces

cadmium distribution in soils covering jurassic oolitic limestone with high cd contents in the swiss jura abstract oolitic carbonates belonging to the hauptrogenstein formation of bajocian middle jurassic age have been shown to be anomalously enriched in cadmium cd throughout the jura mountains soils associated with this type of rock substratum may be naturally polluted with regards to cd at schleifenberg canton basel land switzerland the hauptrogenstein formation is almost entirely exposed along a trail on its sw flank cadmium concentrations were systematically measured throughout this formation and cd enrichments in rocks are shown to occur to a maximum content of 4 9 mg kg 1 we investigated associated soils which cover the entire outcrop and show that they have been formed through the weathering of the underlying bedrock and through the uptake of colluvial limestone fragments from the same and older formations cadmium contents in the soils reach a maximum value of 2 0 mg kg 1 thereby exceeding the official swiss indicative guideline value for soils fixed at 0 8 mg kg 1 mineralogical analyses on the soils and associated bedrock suggest that no allochthonous component related to aeolian transport is present sequential extractions applied to selected soil samples show that about half of the cd resides in the carbonate fraction coming from the fractured parent rock while the cd released from the weathered carbonates is associated either with organic matter over 10 or with fe and mn oxihydroxides approximately 30 no exchangeable cd phase was found and this together with the buffer capacity of this calcareous soil suggests that the amount of mobile cd is quite negligible in this soil which also greatly reduces the amount of bioavailable cd

reflectance spectroscopy of plagioclase dominated mineral mixtures implications for characterizing lunar anorthosites remotely anorthositic rocks dominate the moon s upper crust as remnants of the lunar magma ocean lmo small variations in the mineralogy of these rocks may hold key information about the homogeneity of lmo composition and solidification processes orbital near infrared nir sensors are sensitive to mineralogy but technologic advances have only recently enabled detection of the plagioclase component in crustal rocks based on an absorption band centered near 1250 nm anorthosites occupy a unique mineralogic range that is well suited for nir studies the highly transparent component plagioclase is present in high abundances while the spectrally dominant mafic or oxide minerals are present in only minor abundance as a result spectra of anorthosites are more likely than many other rock types to contain visually discernable signatures from more than one mineral component facilitating their identification and characterization in nir data in support of new nir measurements for the moon we present laboratory spectral analyses of well controlled plagioclase dominated mineral mixtures we focus on the spectral effects of varying mafic and oxide composition and abundance in mixtures with a common plagioclase end member the results demonstrate that plagioclase can be a significant contributor to reflectance spectra when strongly absorbing minerals are present in low abundance we show that the contribution of plagioclase is more pronounced in mixtures with pyroxenes and certain spinels but more easily masked in mixtures containing small amounts of olivine differences in minor mineral composition are clearly expressed in bulk spectra modeling of mixtures using a hapke nonlinear approach accurately estimates mineral abundances in laboratory spectra to within 5 vol for mixtures with 90 vol plagioclase together these results imply that not only should orbital nir data sets be able to discern the presence of plagioclase in anorthositic crustal exposures but also that detailed information about anorthosite mineral assemblages can be reliably accessed in reflectance spectra

nutrient influence on fossil carbonate factories evidence from sedex extractions on burdigalian limestones miocene nw italy and s france abstract different miocene shallow water carbonate successions have been examined to test the potential of phosphorus sequential extraction sedex in studying palaeo nutrient levels and to investigate nutrient influence on carbonate factories during this epoch the coralline algal dominated sequence of the pietra da cantoni group nw italy and the bryozoan dominated sequence of the sommieres basin s france have been targeted for this study actually albeit they both developed during the burdigalian in the very same latitudinal zone they present remarkably different carbonate factories palaeontological analyses have investigated the distribution of the major groups of carbonate producing organisms throughout the successions these results have been compared with those of geochemical analyses on phosphorus and organic matter abundance testifying a clear relationship between the skeletal assemblage and the availability of nutrients as expected on the basis of modern oceanography and benthic ecology bioavailable phosphorus concentration was higher in the bryozoan dominated basin than in the coralline algal dominated basin this result strongly supports sedex sequential extraction as a viable instrument to investigate the nutrient supply in the geological record this also proves that the early miocene mediterranean carbonate factories were deeply controlled by nutrient influence with patterns similar to those observed in present day oceans moderate nutrient concentrations resulted in coralline algal dominance while high nutrient concentrations produced carbonate factories dominated by heterotrophs suspension feeders like bryozoans the euphotic zone producers which dominate in classical tropical associations were probably restricted to areas with low nutrient concentrations

moist dynamics and orographic precipitation in northern and central california during the new year s flood of 1997 abstract the dynamics of moist orographic flows during the january 1997 floods in northern and central california are investigated using numerical simulations computed with the fifth generation pennsylvania state university national center for atmospheric research psu ncar mesoscale model mm5 early in the event 31 december 1996 1 january 1997 the low level winds offshore of california s central coast were blocked by the topography of the santa lucia range and the low level winds in the central valley were blocked by the topography of the central sierra nevada range in contrast moisture laden winds along the northern coast ranges and the northern sierra nevada flowed over topographic barriers as the core of humid air migrated to the south over 24 h the low level barrier jets weakened as the atmospheric stability decreased bringing heavy rainfall to the central and southern sierra nevada at the end of the event the heavy precipitation during this event was largely controlled by the interactio

effect of stable layer formation over the po valley on the development of convection during map iop 8 during intensive observation period iop 8 of the mesoscale alpine program there was a stable layer of air in the lowest levels of the po valley and just upstream of the apennines in this study the effects of the stable layer on the formation of convection in the southern alpine region were investigated through a series of two dimensional idealized experiments the goals of this study were twofold 1 to determine if stable layer strength affected the placement of convection and 2 to test the notion that the stable layer during iop 8 behaved as an effective mountain to accomplish the first objective three simulations were compared in which the strength of the inversion and low level cooling in the po valley and upstream of the apennines was varied the results of these simulations show that the stronger the inversion and low level cooling the farther south the convection was positioned additionally it was found that convection developed as a result of the formation of a broad region of moist instability over the stable layer cellular convection developed in this region of moist instability the second objective was tested through a simulation where the cold pool was replaced by terrain mmtn as in the reference or stb10 simulation the upslope of the terrain in the mmtn simulation was characterized by a wide zone of moist instability however wave structures to the lee of the apennines were markedly different in the stb10 and mmtn simulations this led to different convective and precipitation patterns with the mmtn simulation exhibiting heavier convection over the po valley while the heaviest convection in stb10 was upstream of the apennines these results suggest that at best the stable layer in the stb10 simulation can only be roughly approximated by terrain

low froude number flow past three dimensional obstacles part i baroclinically generated lee vortices abstract we study the flow of a density stratified fluid past a three dimensional obstacle using a numerical model our special concern is the response of the fluid when the froude number is near or less than unity linear theory is inapplicable in this range of froude number and the present numerical solutions show the rich variety of phenomena that emerge in this essentially nonlinear flow regime two such phenomena which occupy parts i and ii of this study are the formation of a pair of vertically oriented vortices on the lee side and a zone of flow reversal on the windward side of the obstacle the ice vortices have been explained as a consequence of the separation of the viscous boundary layer from the obstacle however this boundary layer is absent by design in the present experiments and lee vortices still occur we argue that a vertical component of vorticity develops on the lee side owing to the tilting of horizontally oriented vorticity produced baroclinically as the isentropes deform in r

the distribution and purity of anorthosite across the orientale basin new perspectives from moon mineralogy mapper data 1 the orientale basin is a multiring impact structure on the western limb of the moon that provides a clear view of the primary lunar crust exposed during basin formation previously near infrared reflectance spectra suggested that orientale s inner rook ring irr is very poor in mafic minerals and may represent anorthosite excavated from the moon s upper crust however detailed assessment of the mineralogy of these anorthosites was prohibited because the available spectroscopic data sets did not identify the diagnostic plagioclase absorption feature near 1250 nm recently however this absorption has been identified in several spectroscopic data sets including the moon mineralogy mapper m3 enabling the unique identification of a plagioclase dominated lithology at orientale for the first time here we present the first in depth characterization of the orientale anorthosites based on direct measurement of their plagioclase component in addition detailed geologic context of the exposures is discussed based on analysis of lunar reconnaissance orbiter narrow angle camera images for selected anorthosite identifications the results confirm that anorthosite is overwhelmingly concentrated in the irr comparison with nonlinear spectral mixing models suggests that the anorthosite is exceedingly pure containing 95 vol plagioclase in most areas and commonly 99 100 vol these new data place important constraints on magma ocean crystallization scenarios which must produce a zone of highly pure anorthosite spanning the entire lateral extent of the 430 km diameter irr

orographic precipitation and air mass transformation an alpine example a case of orographic precipitation in the alps on 20 september 1999 was studied using several models along with rain gauge and radar data the objective of the study is to describe the orographic transformation of an air mass including multi scale aspects several new and some conventional diagnostic quantities are estimated including drying ratio precipitation efficiency buoyancy work condensed water residence time parcel changes in heat moisture and altitude and dominant space and time scales for the case considered the drying ratio was about 35 precipitation efficiency values are ambiguous due to repeated ascent and descent over small scale terrain the sign of buoyancy work changed during the event indicating a shift from stratiform orographic to weak convective clouds cloud water residence times are different for the two mesoscale models 400 compared to 1000 s due to different cloud physical formulations the two mesoscale models agree that the dominant spatial scale of lifting and precipitation is about 10 km smaller than the scale of the main alpine massif trajectory analysis of air crossing the alps casts doubt on the classic model of fohn few parcels exhibit classic pattern of moist ascent followed by dry descent parcels that gain latent heat descend only briefly before rising into the middle troposphere parcels that descend along the lee slope originate in the middle troposphere and gain little or even lose latent heat during the transit as parcels seek their proper buoyancy level downstream a surprising scrambling of the air mass occurs radar data confirm the model prediction that the rainfall field is tightly controlled by local terrain on scales as small as 10 km rather than the full 100 km cross alpine scale a curious pulsing of the precipitation is seen indicating either drifting moisture anomalies or weak convection copyright 2003 royal meteorological society

radar observations of precipitation and airflow on the mediterranean side of the alps autumn 1998 and 1999 this study constructs and analyses composite three dimensional fields of doppler radar observed radial velocity and reflectivity for all precipitation events occurring in the lago maggiore region on the mediterranean side of the alps during autumn 1998 and 1999 mean patterns for the two years are in close agreement with each other the radar data are consistent with previous rain gauge studies in showing that the rain was heaviest over the lower windward slopes and decreased toward higher terrain the three dimensional reflectivity fields show that precipitation growth occurred mainly at low altitudes the composite radar data show that the precipitation was most intense when the mean flow around the 2 km level was southerly or south easterly i e when the mean flow was most perpendicular to the alpine barrier sounding data from milan indicated the froude number of the flow upstream of the lago maggiore region when the froude number was high the flow proceeded directly up and over the terrain of the lower alpine slopes under these unblocked conditions the low level flow including the layer from the surface to 2 km above mean sea level rose directly up and over the terrain and the precipitation was greatly enhanced over the lower windward slopes and over the portions of the po valley just upstream of the mountains under unblocked conditions the precipitation enhancement only extended a short distance a few tens of kilometres upstream of the alps when the upstream froude number computed from the milan sounding was low blocked conditions the doppler radial velocities indicated that the low level flow in the layer below 2 km above mean sea level turned cyclonically as it approached the alpine barrier instead of rising over the terrain the composite radar reflectivity data showed less precipitation enhancement directly over the windward slope but in contrast to the unblocked case showed that the precipitation was enhanced 140 km or more upstream of the terrain evidently the low level flow began rising far in advance of the barrier in blocked conditions the 1998 and 1999 autumn data sample further indicates the relative roles of wind speed and stability which are combined in the froude number when the wind speed upstream was strong 8 m s 1 significant precipitation enhancement occurred on the windward slope of the alps in the lago maggiore region regardless of the static stability however the enhancement was far greater under unstable conditions when the wind speed was weak 8 m s 1 the precipitation was generally near or below average except when the stability was low and some patchy enhancement occurred over the po valley just upwind of the alps a diurnal precipitation maximum occurred in the early morning hours 0700 1000 lst possibly where down valley flow converged with synoptic scale up valley flow

core solidification and dynamo evolution in a mantle stripped planetesimal the physical processes active during the crystallization of a low pressure low gravity planetesimal core are poorly understood but have implications for asteroidal magnetic fields and large scale asteroidal structure we consider a core with only a thin silicate shell which could be analogous to some m type asteroids including psyche and use a parameterized thermal model to predict a solidification timeline and the resulting chemical profile upon complete solidification we then explore the potential strength and longevity of a dynamo in the planetesimal s early history we find that cumulate inner core solidification would be capable of sustaining a dynamo during solidification but less power would be available for a dynamo in an inward dendritic solidification scenario we also model and suggest limits on crystal settling and compaction of a possible cumulate inner core

dynamics of metal silicate separation in a terrestrial magma ocean in a terrestrial magma ocean the metal silicate separation involved small metal droplets our goal is to better understand the dynamics of the metal droplet scenario the mechanism of sedimentation in a vigorously convecting and strongly rotating magma ocean may differ significantly from settling droplets in a still fluid in order to systematically study the parameter dependence on the style of motion we utilize two dimensional and three dimensional numerical convection models combined with a tracer based sedimentation method we investigate the characteristic flow patterns resulting from the competing effects of convection and droplet settling and find three styles of motion a temperature dominated style where most droplets remain suspended a droplet dominated style where the droplets separate from the fluid and a style of repetitive motion we find that the droplet dominated style is relevant to the magma ocean in this scenario the droplets settle and form a dense bottom layer one of the key findings of this work is that the formation of the dense bottom layer and therefore the separation of metal droplets from the liquid silicate occurs on a characteristic timescale which is identical with the stokes settling time finally we study the chemical interaction of settling metal droplets and liquid silicate and discuss how accurately a simple parameterized model can describe the chemical equilibration in the metal rain scenario of a terrestrial magma ocean we find agreement between the parameterized model and our two dimensional model our simulations which include thermal convection into the metal rain model confirm the fundamental observation that metal droplets are not permanently suspended in the convecting silicate melt but that they sink and rapidly form a dense layer at the base of the magma ocean

a multiscale analysis of the extreme weather events over western russia and northern pakistan during july 2010 abstractthis manuscript presents a detailed multiscale analysis using observations model analyses and ensemble forecasts of the extreme heat wave over russia and historic floods over pakistan during late july 2010 with an emphasis on the floods over northern pakistan the results show that recirculation of air and dynamically driven subsidence occurring with the intensification of the blocking anticyclone in late july 2010 were key factors for producing the exceptionally warm temperatures over western russia downstream energy dispersion from the blocking region led to trough deepening northwest of pakistan and ridge building over the tibetan plateau thereby providing the linkage between the russian heat wave and pakistan flood events on the large scale in agreement with previous studies the extratropical downstream energy dispersion and enhanced convective outflow on the large scale associated with the active phase of the madden julian oscillation facilitated the formation of an intense upper level

xenolith digestion in large magma bodies xenolith digestion during sinking in a corrosive magma is treated with a surface controlled dissolution relation suggested from recent experiments on silicate crystals the relation is shown to apply to a wide range of dynamical regimes from analog experiments on nacl dissolution in water using this relation xenolith penetration by sinking into magmas is shown to be strongly dependent on xenolith size crystal sinking is unimportant but sinking of meter sized chunks can be a major process of mass and heat transport in planetary scale magma body evolution this evolution cannot be adequately treated with current information

coupled thermal orbital evolution of the early moon abstract coupled thermal orbital histories of early lunar evolution are considered in a simple model we consider a plagioclase lid overlying a magma ocean overlying a solid mantle tidal dissipation occurs in the plagioclase lid and heat transport is by conduction and melt migration we find that large orbital eccentricities can be obtained in this model we discuss possible consequences of this phase of large eccentricities for the shape of the moon and geochronology of lunar samples we find that the orbit can pass through the shape solution of garrick bethell et al garrick bethell i wisdom j zuber m 2006 science 313 652 but we argue that the shape cannot be maintained against elastic deformation as the orbit continues to evolve

active post depositional oxidation of the most recent sapropel s1 in sediments of the eastern mediterranean sea abstract over a wide area of the eastern mediterranean basin two mn rich layers have been observed above the most recent sapropel s1 one immediately above the sapropel top and one a few centimetres closer to the sediment surface different mechanisms have been proposed to explain the occurrence of these two mn peaks either both peaks have a diagenetic origin in which case the upper mn peak is actively forming or the lower peak is actively forming and the upper peak has a different formation mechanism high resolution porewater including a gel sampler used for the first time in marine sediments and solid phase data are now used to demonstrate that the oxidation front is located at the level of the lower mn peak which therefore is presently being formed a barium organic carbon relationship is used to calculate the initial organic carbon profile of the s1 sapropel the palaeoproductivity profiles generated by this method demonstrate that the original sapropel unit was bounded by the upper mn peak this implies that the interval between the two mn peaks where a low organic carbon content is now observed was originally part of the sapropel the initially deposited organic carbon has been oxidised by a progressive downwards moving oxidation front the penetration depth of this oxidation front i e the distance between the two mn peaks is mainly determined by the organic carbon content the sediment accumulation rate and the bioturbation depth the upper mn peak appears to have formed as a result of either mn precipitation upon oxygenation of previously anoxic eastern mediterranean deep water or preservation of a surficial mn peak at the end of the high productivity episode in either case the upper mn peak marks the end of sapropel formation as indicated by the ba profiles this means that formation of the s1 sapropel ceased more recently than is indicated by radiocarbon dating of the visible top of s1

nonfractional crystallization of a terrestrial magma ocean it has been suggested that evolution of a terrestrial magma ocean does not unavoidably follow a fractional crystallization scenario convection is able to preclude differentiation until a sharp viscosity increase occurs near some critical crystal fraction however this kind of crystallization and its physical and chemical consequences have not been previously studied we consider an end member called here nonfractional crystallization we begin with a simple equilibrium thermodynamical model of partial melts which is based on an ideal three component phase diagram it allows a self consistent calculation of physical and chemical parameters in the melting range at all interesting pressures in particular adiabats of the convecting magma ocean are calculated the sharp increase in the viscosity is supposed to occur near the maximum packing crystal fraction however almost independently of this value convection occurs even in the highly viscous quasi solid part of the magma ocean and it is strong enough to prevent differentiation in deep regions a kind of compositional convection occurs due to the layered differentiation although it is weaker than the thermal convection only a surface region undergoes an essential differentiation via melt expulsion by compaction the thickness of this layer depends on the rheology of partial melts critical crystal fraction and crystal sizes but in any case the basal pressure hardly can exceed 5 10 gpa because of lower pressures in the moon the thickness of the differentiating layer is large and thus the entire lunar magma ocean could undergo a strong differentiation remelting due to the energy released by differentiation is crucial only for much deeper layers possibly deeper than about 1000 km for the earth for the remaining shallow layer p 5 10 gpa the predicted increase of the melt fraction is less than 40 at the surface and decreases to zero at the bottom of the differentiating layer thus the nonfractional crystallization is suggested to be a likely alternative to the fractional crystallization the crucial and still poorly understood factors are suspension in convective layers rheology of partial melts crystal size and surface conditions the most pronounced chemical consequence of the nonfractional crystallization is an almost completely preserved undifferentiated lower mantle and possibly a significant undifferentiated part of the upper mantle at all depths in the beginning of differentiation not only the first liquidus solid phase but also subsequent phases have been partially crystallized so when the differentiation begins it involves mixtures of phases it is important for the remaining layer where differentiation is unavoidable this layer does not have as strong differentiation of minor elements as in the case of fractional crystallization but it will still involve differentiation of major elements future geochemical calculations of this multiphase differentiation considering both major and minor elements could help to constrain the differentiation further

addressing complexity in laboratory experiments the scaling of dilute multiphase flows in magmatic systems the kinematic and dynamic scaling of dilute multiphase mixtures in magmatic systems is the only guarantee for the geological verisimilitude of laboratory experiments we present scaling relations that can provide a more complete framework to scale dilute magmatic systems because they explicitly take into account the complexity caused by the feedback between particles crystal bubble or pyroclast and the continuous phase liquid or gas we consider three canonical igneous systems magma chambers volcanic plumes and pyroclastic surges and we provide estimates of the proposed scaling relations for published experiments on those systems dilute magmatic mixtures can display a range of distinct dynamical regimes that we characterize with a combination of average eulerian properties and instantaneous lagrangian variables the eulerian properties of the mixtures yield the reynolds number re which indicates the level of unsteadiness in the continuous phase the lagrangian acceleration of particles is a function of the viscous drag and gravity forces and from these two forces are derived the stokes number st and the stability number rt two dimensionless numbers that describe the dynamic behavior of the particles within the mixture the compilation of 17 experimental studies relevant for pyroclastic surges and volcanic plumes indicates that there is a need for experiments above the mixing transition ren10 4 and for scaling st and rt among the particle dynamic regimes present in surges and plumes some deserve special attention such as the role of mesoscale structures on transport and sedimentary processes or the consequences of the transition to turbulence on particle gathering and dispersal the compilation of seven experimental studies relevant to magma bodies indicates that in the laminar regime crystals mostly follow the motion of the melt and thus the physical state of the system can be approximated as single phase in the transition to turbulence magmas can feature spatially heterogeneous distributions of laminar regions and important velocity gradients this heterogeneity has a strong potential for crystals sorting in conclusion the re st rt framework demonstrates

did the orientale impact melt sheet undergo large scale igneous differentiation by crystal settling significant quantities of shock induced melt are predicted to form during basin scale impact events and may contribute substantially to compositional variation in the lunar crust through differentiation processes knowledge of the evolution of impact melt sheets and the cooling and crystallization processes involved is therefore important to understanding the geology and petrology of the moon here we perform a case study on the orientale basin and investigate the possibility of differentiation of the impact melt sheet by assessing the thermal and physical processes that drive cooling and crystallization focusing on crystal settling results predict that convective processes within the impact melt sheet enhance cooling and solidification and inhibit settling of crystals 1 5 mm in diameter and smaller preventing differentiation at or below this size impact melt sheet thickness is predicted to have minimal influence on crystallization history suggesting that crystal size is the primary factor controlling lunar impact melt sheet differentiation

plagioclase chain networks in slowly cooled basaltic magma plagioclase crystals in the slowly cooled interior of the thick holyoke flood basalt flow of connecticut linked to form monomineralic chains at an early crystallization stage partial melting experiments reveal that when the quartz tholeiite was only 25 crystallized the chains had already linked to form a continuous 3 d network at such an early stage of crystallization the network was weak highly permeable and easily deformed consequently the mush of plagioclase chains and interstitial pyroxene crystals underwent compaction in the lower third of the flow with the expelled liquid rising to the center of the flow where it crystallized to form coarse grained sheets of fractionated basalt plagioclase chains are most easily seen in the basalt after it has been partly melted and the late crystallizing minerals converted to glass the chains are several crystals wide the crystals which are approximately 0 5 mm long are attached together randomly normal zoning patterns indicate crystals had a brief period of growth before linking together the chains branch every few millimeters to form the 3 d network which was mapped using serial polished sections and x ray ct scans the chain frequency measured along vertical and horizontal traverses decreases toward the center of the flow in the compaction zone the frequency in the vertical direction is greater than in the horizontal making the reasonable assumption that these frequencies were initially the same the difference is used to calculate the degree of compaction the resulting pattern through the flow matches almost exactly the pattern indicated by variations in the incompatible elements plagioclase chains are also found in some coarser grained plutonic rocks if they are common their fabric may provide a new direct means of measuring the degree of compaction in crystal mushes

further results on moist nearly neutral flow over a ridge abstract in a recent study the authors performed numerical simulations of moist nearly neutral flows over a ridge using the weather research and forecasting wrf model in a regime where the coriolis force can be neglected and with the simple kessler warm rain microphysical scheme in the present work further numerical solutions using more general and realistic experimental conditions are discussed the upstream propagating disturbance which was found in the author s previous study to desaturate the initially saturated sounding for intermediate mountain heights is present for all the simulations with taller mountains considered in the present work the inclusion of the coriolis force however suppresses the upwind propagation of the dry region and weakens the downstream development of convective cells the sensitivity to different microphysical schemes has also been investigated the simple kessler scheme was compared with a more complete scheme by lin et al which includes ice species some differ

crystal mat formation as an igneous layering forming process textural and geochemical evidence from the lower layered nepheline syenite sequence of the ilimaussaq complex south greenland abstract the lower layered nepheline syenite sequence kakortokites of the mesoproterozoic alkaline to peralkaline ilimaussaq complex south greenland shows spectacular rhythmic meter scale igneous layering the 29 exposed units have sharp contacts against each other and each of these units consists of three modally graded layers dominated by arfvedsonitic amphibole eudialyte group minerals and alkali feldspar respectively this study uses field observations on changes in mineral orientation recurrent mineral textures compositional data from eudialyte group minerals and amphibole and settling rate calculations based on a modified stokes equation to explain the igneous layering of the kakortokites we propose that the three major cumulus minerals amphibole eudialyte s l and alkali feldspar were separated from each other by density contrasts resulting in modally graded layers within each unit the densest of these three minerals amphibole formed crystal mats within the cooling magma body these crystal mats acted as barriers that inhibited large scale vertical migration of melts and crystals with increasing effectiveness over time the sub volumes of magma captured in between the crystal mats evolved largely as geochemically independent sub systems as indicated by the observed trends in mineral composition

zinc rich clays in supergene non sulfide zinc deposits the nature and the origin of zinc clays are poorly understood with the example of the bou arhous zn pb ore deposit in the moroccan high atlas this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non sulfide zinc ores in the field white to ocher granular clays are associated with willemite zn2sio4 while red clays fill karst related cavities cutting across the non sulfide ore bodies red clays kaolinite chlorite illite and smectite present evidence of stratification that reflects internal sedimentation processes during the karst evolution white clays contain 7 a clay mineral smectite irregular interstratified minerals with less than 20 of smectite layers willemite is partially dissolved and is surrounded by authigenic zinc clay minerals together with xrd results wds analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite cec measurements support that zinc is only located within the octahedral sheets these new results support the following process i dissolution of willemite leading to release of si and zn ii interaction between zn si rich solutions and residual detrital clays and iii dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas

early differentiation of the moon evidence from trace elements in plagioclase bulk samples and plagioclase mineral grains from lunar cataclastic ferroan anorthosites were analyzed for trace elements by instrumental neutron activation analysis some pure plagioclase crystals have lower concentrations of cr co sc and heavy rees than previous analyses indicated concentrations of sr eu na ga and the rees in plagioclases from different anorthosites vary in a systematic way and the trace element patterns of plagioclases from pristine norites and troctolites are very different from the plagioclase pattern of anorthosites the following model is suggested to account for these observations 1 melting of a large fraction of the moon formation of a magma ocean precipitation of olivine and later pyroxene followed by flotation of cumulus plagioclase 2 mixing of kreep with a mafic component enriched in mg cr and co 3 precipitation of noritic and troctolitic cumulates and metallic iron from this magma and 4 eruption of these kreep and mg rich lavas and or distribution of these materials over the front side of the moon by basin forming impacts 3 9 4 0 b y ago

numerical simulations of the 12 13 august 2002 flooding event in eastern germany in this paper high resolution numerical simulations of the 12 13 august 2002 flooding event in eastern germany are presented the simulations are performed with the penn state national center for atmospheric research mesoscale model mm5 in a four domain configuration with a finest horizontal resolution of 1 km sensitivity experiments are performed with coarser resolutions 3 and 9 km with different cloud microphysical parametrizations and with a different date of initialization moreover tests with i km resolution but the smoothed topography of the 9 km runs are conducted in order to isolate the contribution of the model topography to the differences between the 1 km runs and the 9 km runs the results show that the high resolution runs reproduce the observed structure of the precipitation field very well in particular the location of the rainfall maximum is correct to within 15 km the quantitative agreement between model results and observations is fairly good in regions with light to moderate rain but large amounts of precipitation tend to be underpredicted for observed 36 hour rainfall accumulations exceeding 200 mm the negative bias typically ranges between 15 and 30 with fairly little dependence on the microphysical parametrization in the coarser resolved runs the bias at high precipitation amounts becomes even more pronounced and it is found that this behaviour is not only due to the fact that a coarser resolution is associated with a smoother topography this indicates a systematic deficiency in the microphysical parametrizations limiting their ability to simulate heavy precipitation

lunar magma transport phenomena abstract an understanding of the most significant events during the first ga or so of lunar history global differentiation associated with a lunar magma ocean lmo and the later generation of about 107 km3 of mare basalts depends profoundly on magma transport dynamics lmo evolution is dominated by the characteristics of hard turbulent convection of a fluid undergoing phase change quench protocrust formed at the ocean surface in early times is repeatedly disrupted by bolide impact ocean body tides and associated crustal foundering during this epoch the ocean temperature is set by the balance between convective heat brought to the surface and brown body radiation from the surface at later times the convective flow is organized into a number of regimes from top to bottom these include conductive crustal lid a viscous sublayer an inertial core a lower viscous sublayer and a mushy cumulate region crystal settling and flotation is restricted to the viscous sublayer regions dilatancy pumping may prevent the efficient expulsion of intercumulus melt during cumulate formation typical velocities within the inertial region are of order 10 m s because late stage ti rich cumulates are dense relative to the earlier mg rich cumulates hyper to sub solidus convection tends to mix lmo crystallization products numerical simulations that account simultaneously for compositional and thermal buoyancy effects indicate a characteristic mixing time 200 ma statistical measures of mixing variance and spatial correlation length quantify the details of mixing the darcy percolative and vein drain models of melt extraction are briefly discussed because compaction lengths are small 102 m the rate of melt extraction is governed by the balance between melt buoyancy and darcy friction differential melt matrix velocities are of order 10 km ma for nominal values appropriate for mare basalt melt extraction from a heterogeneous mixed lmo source transport of magma through the lunar lithosphere via a connected crack network seems highly probable for the range of inferred discharge rates applicable for lunar mare volcanism lmv 103 to 107 m3 s typical fracture widths and ascent speeds are 10 1 to 50 m and 10 1 to 10 m s respectively a simple model is proposed to evaluate the extent of fractionation as magma traverses cold lunar lithosphere if apollo green glasses are primitive and have not undergone significant fractionation en route to the surface then mean ascent rates of 10 m s and cracks of widths 40 m are indicated lunar tephra and vesiculated basalts suggest that a volatile component plays a role in eruption dynamics the predominant vapor species appear to be co co2 and cos near the lunar surface the vapor fraction expands enormously and vapor internal energy is converted to mixture kinetic energy with the concomitant high speed ejection of vapor and pyroclasts to form lunar fire fountain deposits such as the apollo 17 orange and black glasses and apollo 15 green glass

modeling phase separation and phase change for magma ocean solidification dynamics just after accretion the earth s mantle was significantly molten by the heat dissipation due to large impacts and to the segregation of the core the mineralogical observations and thermodynamics models of solid liquid equilibrium of silicates show that several types of crystallization may have happened at different depths in the mantle solids were probably formed first at the bottom of the lower mantle or at mid mantle leaving two possible magma oceans a shallow one and an abyssal one near the bottom of the mantle the liquid phase might become denser than solids due to iron enrichment in the shallow magma ocean the crystallizing solid phase was denser and sank through the magma to settle and compact at depth to understand these complex dynamics we develop a two phase numerical code that can handle simultaneously convection in each phase and in the slurry and the compaction or decompaction of the two phases although our code can only run in a parameter range rayleigh number viscosity contrast between phases prandlt number far from what would be realistic we think it already provides a rich dynamics that illustrates what could have happened we show situations in which the crystallization front is gravitationally stable and situations were the newly formed solids are gravitationally unstable and can snow across the magma our study suggests that the location of a density contrast between solid and magma must be considered of equal importance with that of the intersection between liquidus and isentrope for what concerns mantle solidification

global assessment of pure crystalline plagioclase across the moon and implications for the evolution of the primary crust recent advancements in visible to near infrared orbital measurements of the lunar surface have allowed the character and extent of the primary anorthositic crust to be studied at unprecedented spatial and spectral resolutions here we assess the lunar primary anorthositic crust in global context using a spectral parameter tool for moon mineralogy mapper data to identify and map fe bearing crystalline plagioclase based on its diagnostic 1 25 m absorption band this allows plagioclase dominated rocks specifically anorthosites to be unambiguously identified as well as distinguished from lithologies with minor to trace amounts of mafic minerals low spatial resolution global mosaics and high spatial resolution individual data strips covering more than 650 targeted craters were analyzed to identify and map the mineralogy of spectrally pure regions as small as 400 m in size spectrally pure plagioclase is identified in approximately 450 targets located across the lunar surface diviner thermal infrared tir data are analyzed for 37 of these nearly monomineralic regions in order to understand the compositional variability of plagioclase an in these areas the average an for each spectrally pure region is estimated using new laboratory measurements of a well characterized anorthite an96 sample diviner tir results suggest that the plagioclase composition across the lunar highlands is relatively uniform high in calcium content and consistent with plagioclase compositions found in the ferroan anorthosites an94 98 our results confirm that spectrally pure anorthosite is widely distributed across the lunar surface and most exposures of the ancient anorthositic crust are concentrated in regions of thicker crust surrounding impact basins on the lunar nearside and farside in addition the scale of the impact basins and the global nature and distribution of pure plagioclase requires a coherent zone of anorthosite of similar composition in the lunar crust supporting its formation from a single differentiation event like a magma ocean our identifications of pure anorthosite combined with the grail crustal thickness model suggest that pure anorthosite is currently observed at a range of crustal thickness values between 9 and 63 km and that the primary anorthositic crust must have been at least 30 km thick

climatology of extreme rainfall and flooding from orographic thunderstorm systems in the upper arkansas river basin 1 analyses of the spatial and temporal distribution of extreme rainfall in the arkansas river basin above pueblo colorado are based on volume scan reflectivity observations from the pueblo wsr 88d radar during the period 1995 2003 a storm catalog of 66 rainfall events during the 9 year period has been developed climatological analyses of extreme rainfall are carried out both from an eulerian perspective in which distributional aspects of rainfall at fixed locations are examined and from a lagrangian perspective in which distributional aspects of rainfall are based on storm tracking algorithms of particular interest is the spatial heterogeneity of extreme rainfall in the complex terrain of the upper arkansas river basin lagrangian analyses are used to characterize the spatially varying distribution of storm initiation storm motion and storm structure climatological analyses indicate that convective rainfall in the arkansas river basin above canon city drainage area of 8070 km2 does not contribute to the extreme flood response of the arkansas river at pueblo drainage area of 12 140 km2 there is pronounced diurnal variation in warm season rainfall in the arkansas river basin and this feature of extreme rainfall is a key element of flood response in the upper arkansas river basin climatological analyses of extreme rainfall in the upper arkansas river basin are examined relative to the spatial and temporal properties of rainfall for extreme flood events that have occurred in the basin including major flood episodes in june 1921 and june 1965

origin of lunar high titanium ultramafic glasses constraints from phase relations and dissolution kinetics of clinopyroxene ilmenite cumulates abstract phase equilibrium and dissolution kinetics experiments on synthetic late stage magma ocean cumulates are used to place constraints on hypotheses for the origin of lunar high ti ultramafic glasses models for the production of high ti lunar magmas have called for either 1 assimilation of late stage clinopyroxene ilmenite cumulates at shallow levels or 2 sinking of clinopyroxene ilmenite cumulates to form a hybrid mantle source to satisfy the constraints of our experiments we propose an alternative model that involves shallow level reaction and mixing of cumulates followed by sinking of hybrid high ti materials this model can fulfill compositional requirements imposed by the pristine lunar glass suite that are difficult to satisfy in assimilation models it also avoids difficulties that arise in overturn models from the low solidus temperatures of clinopyroxene ilmenite cumulates partially molten clinopyroxene ilmenite cumulates become gravitationally unstable with respect to underlying mafic cumulates only when they have cooled to within 30 c of their solidus 1125 c at 100 km depth at these temperatures the viscosity of mafic cumulates is too high to allow for growth and descent of clinopyroxene ilmenite diapirs on the appropriate time scale reaction and mixing between late stage liquids and mafic cumulates at shallow levels would produce a refractory hybrid material that is negatively buoyant at higher temperatures and could sink more efficiently to the depths inferred for production of high ti ultramafic glasses

a model aided investigation of winter thermally driven circulation on the italian tyrrhenian coast a case study 1 data collected during a campaign carried out in and around rome in february 1996 using sodars tethered balloon and surface data suggest the development of a winter sea breeze that could not be detected by conventional data and analyses a model aided study is performed to verify the development of thermally driven local circulation and to prove the onset of a winter sea breeze regime propagating inland and interacting with the urban heat island uhi the area of interest for the study is the central part of italy latitude 41 43n longitude 10 16e the mm5 mesoscale model was used at high resolution three nested domains with up to 3 km of grid resolution were used in the area where the sea breeze was observed to highlight the effect of the sea breeze a simulation with a thick cloud layer in the innermost domain was performed by removing the cloud layer the diurnal evolutionofthehorizontaltemperature gradientledtothedevelopmentoftheseabreezeand the uhi circulation in agreement with the data sensitivity tests were carried out to evaluate the effect of land use resolution and of satellite retrieved climatological sea surface temperatureonthesimulationresults doppler sodardatarecordedatthreesites tethersonde profiles and surface data were used to verify the results as expected using high resolution land use and the daily sea surface temperature retrieved by satellite observations led to improvementsinthelocalcirculationproducedbythemodel however themodelfallsshort in reproducing some of the sea breeze characteristics it finds that the sea breeze starts too early and lasts for a shorter time than the observed one does and the wind direction shows a too strong northerly component also it slightly underestimates the daily temperature pattern the interaction of the urban heat islands of rome and ostia with the sea breeze flow is analyzed to explain the causes of these discrepancies index terms 3307 meteorology and atmospheric dynamics boundary layer processes 3322 meteorology and atmospheric dynamics land atmosphere interactions 3329 meteorology and atmospheric dynamics mesoscale meteorology keywords sea breeze modeling urban heat island citation ferretti r g mastrantonio s argentini r santoleri and a viola a model aided investigation of winter thermally driven circulation on the italian tyrrhenian coast a case study j geophys res 108 d24 4777 doi 10 1029 2003jd003424 2003

mechanisms of intense alpine rainfall abstract numerical studies by the authors and others of the 1994 piedmont flood show that the orographically modified flow was a critical element for the production of extraordinary rainfall to uncover the precise mechanism of orographic rainfall occurring in full physics mm5 simulations of the 1994 piedmont flood the authors carried out simulations with the same real data initial and boundary conditions but with the real orography replaced by an idealized one with excellent agreement between real and idealized orography on the rainfall rate versus time in the piedmont area analysis of the idealized orography simulation provides a clear picture of the model s mechanism of orographically induced rainfall as noted in previous studies of the 1994 piedmont case a moist saturated airflow has a reduced effective static stability and tends to flow over the mountains while an unsaturated airstream is stable and tries to flow around toward the left in the northern hemisphere in the 1994 piedmont case t

layered intrusions and traffic jams a wide range of explanations has been proposed for the origin of repetitive layering in mafic ultramafic and in per alkaline intrusions here we propose that the interaction of mineral grains that sink and float in the crystallizing magma is an alternative mechanism that can explain many of the features of layered intrusions without the need to invoke extrinsic factors similar to traffic jams on a motorway small perturbations in crystal density develop that impede further ascent or descent of buoyant or heavy minerals respectively these traffic jams separate layers of magma from the rest of the magma chamber the magma in the individual layers further evolves as a largely independent subsystem with gravitational sorting organizing the mineral distribution within each layer layering can develop in the intermediate range between full mineral separation in low viscosity or slowly cooling magma chambers and homogeneous crystallization in high viscosity or fast cooling chambers this self organization mechanism provides a novel explanation for the formation of rhythmic layering in low viscosity magmas for example in the ilimaussaq igneous complex in southwest greenland

apollo 14 very low titanium glasses melting experiments in iron platinum alloy capsules this paper describes two techniques that have been developed to produce fe pt alloy capsules for high pressure experiments and reports liquidus phase relations of the apollo 14 very low titanium glasses determined using fe rich capsules afe 0 6 the liquid is multiply saturated with olivine and clinopyroxene at 22 kbar the multiple saturation is at least 3 kbar higher than that determined using pure fe capsules and corresponds to a source region at least 60 km deeper if olivine and clinopyroxene were the residual phases however we still need independent data on iron activity or oxygen fugacity of the glasses in order to choose a container of optimum composition preliminary experiments in fe poor alloy capsules suggest that the valence state of iron and the crystallization sequence in the melt have changed possibly as a result of oxidizing materials entrapped during the iron plating processes the feo content of the charge decreases linearly with increasing run duration in experiments using pure fe capsules the observation that iron rich globules grow with time suggests that the equilibrium fe bleb fe2o3 liq 3 feo liq might be established in the liquid at high pressure if this explanation is correct an appreciable amount of feo in the liquid could actually be fe2o3 and some natural lunar volcanic glasses may contain ferric iron as well

a low viscosity lunar magma ocean forms a stratified anorthitic flotation crust with mafic poor and rich units much of the lunar crust is monomineralic comprising 98 plagioclase the prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean lmo whether 98 pure anorthosites can form in a flotation scenario is debated an important determinant of the efficiency of plagioclase fractionation is the viscosity of the lmo liquid which was unconstrained here we present results from new experiments conducted on a late lmo relevant ferrobasaltic melt the liquid has an exceptionally low viscosity of 0 22 0 19 0 11 to 1 45 0 82 0 46 pa s at experimental conditions 1 300 1 600 c 0 1 4 4 gpa and can be modeled by an arrhenius relation extrapolating to lmo relevant temperatures our analysis suggests a low viscosity lmo would form a stratified flotation crust with the oldest units containing a mafic component and with very pure younger units old impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario

thermal and magmatic evolution of the moon as with all science our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data this process invigorates the intellectual foundation on which old models are tested and new concepts are built just as the application of new observational tools to lunar science in 1610 galileo s telescope and 1840 photography yielded breakthroughs concerning the true nature of the lunar surface the computational and technological advances highlighted by the apollo and post apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the moon 1 1 pre apollo view of the thermal and magmatic evolution of the moon many of the early views of the moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the sun and the moon prophetically myths involving the lunar deities mwuetsi from zimbabwe and coyolxauhqui from mexico told of rather violent or catastrophic events in which the moon was expunged from the earth numerous ancient scientific observations were made about the nature of the moon ranging from those uncovered in early neolithic sites that correctly identified mare crisium and mare humorum to the insights made by greek philosophers such as anaxagoras ca 500 428 b c and democritus ca 460 370 b c who attached terrestrial analogues to its character stone mountains with the advent of the telescope 1610 and photography 1840 as scientific tools for lunar exploration semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation initially modern terrestrial geological analogs were extended to the moon lunar highlands volcanic craters seas combined with the rigors of computational modeling these observational data were extended to predict the original thermal state of the moon and its thermal and magmatic history its proximity to the earth

radar observations and numerical modeling of a precipitating line during map iop 5 abstract during the special observing period of the mesoscale alpine programme a narrow north south oriented frontal precipitation band was observed by two airborne and one operational doppler radar on 4 october 1999 over the friuli target area in northeast italy convective precipitation was mostly concentrated to the south of the eastern alps in regions of smooth orography and warm southerly flow ahead of the cold front while stratiform rain formed above the mountainous chain where a marked cold northerly flow wrapping around the eastern alps progressed southwestward doppler data collected in both convective and stratiform regions of the precipitation line as well as high resolution numerical simulations performed with the nonhydrostatic meso nh model are used to investigate the associated flow structure in connection with the underlying topography the mutually consistent observed and simulated precipitation and wind fields clearly identify low level flow convergence relative to the cold front

mechanisms producing different precipitation patterns over north eastern italy insights from hymex sop1 and previous events during the first hymex special observation period sop1 field campaign the target site of north eastern italy nei experienced a large amount of precipitation locally exceeding the climatological values and distributed among several heavy rainfall episodes in particular two events that occurred during the last period of the campaign drew our attention these events had common large scale patterns and a similar mesoscale setting characterised by southerly low level flow interacting with the alpine orography but the precipitation distribution was very different during intensive observing period iop18 31 october 1 november 2012 convective systems were responsible for intense rainfall mainly located over a flat area of the eastern po valley well upstream of the orography conversely during iop19 4 5 november 2012 heavy precipitation affected only the alpine area in addition to iop18 and iop19 the present study analyses other heavy precipitation episodes that display similar characteristics and which occurred over nei during the autumn of recent years a high resolution 2 km grid spacing non hydrostatic nwp model and available observations are used for this purpose the two different observed precipitation patterns are explained in terms of interaction between the impinging flow and the alps depending on the thermodynamic profile convection can be triggered when the impinging flow is forced to rise over a pre existing cold air layer at the base of the orography in this situation a persistent blocked flow condition and upstream convergence are responsible for heavy rain localized over the plain conversely if convection does not develop flow over conditions are established and heavy rain affects the alps numerical parameters proposed in the literature are used to support the analysis finally the role of evaporative cooling beneath the convective systems is evaluated it turns out that the stationarity of the systems upstream of the alps is mainly attributable to persistent blocked flow conditions while convective outflow slightly modifies the location of precipitation

thermal and chemical evolution of the terrestrial magma ocean abstract the earth is likely to have experienced a magma ocean stage during accretion thermal and chemical evolution of magma ocean is investigated based on a one dimensional two phase flow heat and mass transfer model differentiation at lower mantle pressure depends on the type of magma ocean and surrounding atmosphere if the magma ocean is formed by the blanketing effect of a solar type proto atmosphere extensive differentiation proceeds at lower mantle pressure if the magma ocean is formed by the blanketing effect of an impact induced steam atmosphere no differentiation at lower mantle pressure is likely if a very deep magma ocean is formed by a giant impact whether differentiation proceeds at lower mantle pressure or not depends on grain size viscosity of melt and or properties of a transient atmosphere on the contrary chemical differentiation likely proceeds at upper mantle pressure irrespective of magma ocean type a shallow magma ocean can remain for 100 200 my without any heating processes

lunar anorthosite 60025 the petrogenesis of lunar anorthosites and the composition of the moon systematic variations of the mineral chemistry of ferroan anorthosite 60025 which is probably a mixture of closely related materials suggest that lunar anorthosites formed by strong fractional crystallization and near perfect adcumulate growth without trapping liquid the parent liquid for the most primitive samples was saturated with olivine plagioclase pigeonite and chromite and evolved to one saturated with plagioclase pigeonite high ca pyroxene and ilmenite the parent liquid also had a very low na2o content and combined with strong fractional crystallization this explains the steep trend of anorthosites on an mg atomic 100 mg mg fe v an diagram the mineral and chemical data for other anorthosites are consistent with such a model near perfect adcumulation can occur if growth takes place at the crystal liquid interface without the physical accumulation of crystals grown elsewhere and is encouraged by the shifts in phase boundaries with pressure anorthosites are probably the remnants of a crust floating on and crystallizing at the surface of a magma ocean originally of bulk moon composition mineralogical and trace element data suggest that the parental liquid for the most primitive anorthosites had previously crystallized no plagioclase and some but perhaps very little pyroxene hence the bulk moon appears to be similar to that proposed by ringwood 1976 but to have even lower alkalis a subchondritic caal ratio and ree abundances and patterns close to chondritic the mare basalt sources are not directly complementary to the feldspathic crust because experimental and trace element data indicate that they are too magnesian and contain too much high ca pyroxene other crustal rocks such as the mg suite samples are not closely related to anorthosites in addition to their chemical differences they have a different crystallization sequence ol plag px in contrast with the ol px plag inferred for anorthosite parental liquid evolution

a numerical study of appalachian cold air damming and coastal frontogenesis abstract a 24 h numerical simulation is used to study features of the wedge shaped pressure ridge and the coastal front which occur in eastern united states during winter and often cause substantial errors in operational models specifically the penn state national center for atmospheric research mesoscale model mm is used as a diagnostic tool to investigate the mesoscale structure of these phenomena associated with the appalachian ice storm of 13 14 january 1980 the mm which used 15 vertical levels 8 below 800 mb a 50 km horizontal mesh size and a multi level boundary layer parameterization produced a better forecast of boundary layer temperature and sea level pressure than did the national meteorological center s operational model for this case study period to the east of the mountains the mm maintained the wedge ridge pattern and produced the low level northerly flow which is characteristic of the damming region the mm also provided reasonable vertical profiles of temperature and wind

the lunar magma ocean reconciling the solidification process with lunar petrology and geochronology abstract the moon is thought to have originated with a magma ocean that produced a plagioclase flotation crust as solidification proceeded ages of anorthositic crust range over at least 200 million years the model for solidification presented here integrates chemical and physical constraints of lunar magma ocean solidification to determine 1 the final thickness of flotation crust generated by a fractionally solidifying magma ocean 2 the timescale of crystallization before plagioclase is a stable phase 3 the timescale of solidification after the formation of the plagioclase flotation crust and 4 the post overturn lunar mantle composition and structure we find that magma oceans of as much as 1000 km depth are consistent with creating an anorthositic crust 40 to 50 km in thickness solidification of the magma ocean prior to formation of the flotation crust may occur on the order of 1000 years and complete solidification would require additional ten to tens of millions of years reconciling these short model timescales with radiometric dates of crustal samples requires either a very late forming moon combined with finding older crustal ages to be incorrect or calling on tidal heating of the crust by the early earth to prolong solidification gravitationally driven overturn of cumulates during tidal heating provides a mechanism for creating the compositions and ages of the lunar mg suite of crustal rocks further we find that upon crystallization the moon likely began with an azimuthally heterogeneous gravitationally stable mantle after magma ocean cumulate overturn this result may help explain the experimentally determined origin of picritic glasses at similar depths but from different source materials

orographic effects on rainfall in map cases iop 2b and iop 8 although the large scale flow was similar important differences in mesoscale atmospheric structure made the difference between moderately intense rain in intensive observing period iop 2b and relatively light rain in iop 8 in the lago maggiore target area lmta this conclusion is supported here through analysis of data from and numerical simulations of these two cases analysis of the large scale data shows that there was in both cases a moist tongue of southerly flow moving from the west to the east of the alpine south side mesoscale data analysis and numerical simulations suggest that the most important difference between the two cases was the presence of a cold stable air mass in the po valley in iop 8 which persisted through the period in which the large scale moist tongue was progressing eastward and prevented the most humid air from reaching the lmta another difference contributing to the greater rainfall in the lmta in iop 2b was the development of conditional instability with associated convective rain due to the effect of the alps on the eastward passage of the moist tongue in iop 8 the atmosphere remained locally stable throughout the period copyright 2003 royal meteorological society

suspension in convective layers and style of differentiation of a terrestrial magma ocean recent physical theories for the formation of the earth suggest that about 4 5 b y ago the mantle of the earth was partially or completely molten fractional crystallization of this hypothetical magma ocean would result in a strong chemical stratification of the earth s mantle such a scenario is controversial from the geochemical point of view however it has been noted that the simple scenario of fractional crystallization could be avoidable in a convective magma ocean if crystals remain suspended in this paper the problem of suspension is developed with the help of an energetic approach convection must do some work against gravitational settling we distinguish three regimes of convective suspensions absolute or complete sedimentation occurs when the energy dissipation due to the settling exceeds the heat loss from the convective layer this is possible only in large scale systems like magma oceans and implies that cooling can proceed only together with sedimentation crystallization and a decrease in the liquidus temperature at a constant pressure a regime of partial differentiation occurs when the energy dissipation due to the settling is less than the total heat loss but larger than the power which can be spent by convection on the crystal reentrainment process the differentiation is not complete and a competition between the rate of cooling the rate of sedimentation and the rate of turbulent diffusion determines the degree of differentiation the third regime is an absolute suspension which could be sustained for an indefinitely long time in this case sedimentation starts only when the crystal fraction reaches the maximum packing value when the viscosity of the magma rapidly increases the power which can be spent by convection on reentrainment is equal to e gd cp of the total energy supply to the convective layer where e 15 gpa or 10 3 10 1 cm during crystallization of shallow layers the first regime fractional crystallization is unavoidable the estimates depend on various poorly constrained parameters and processes such as heat flux viscosity thermodynamical disequilibrium and highly variable viscosity convection for absolute suspension the crystal size must be at least e times less or 10 3 10 1 cm and 10 4 10 2 cm respectively if e 0 01 the partial differentiation occurs in a narrow one decade range between these two regimes the radius of about 1 cm must be considered as an absolute upper bound above which fractional differentiation is guaranteed these estimates for the critical crystal size are orders of magnitude lower than suggested previously and thus the problem of crystal sizes becomes a central one for magma oceans a necessary condition for reentrainment is the existence of local mechanisms the absence of such mechanisms to reentrain the particles from the bottom would mean that an absolute suspension is impossible even if the energetics allows it turbulence is considered as a possible important factor a simple model of convection predicts a strong turbulence provided the viscosity is less than 10 9 10 10 p rotation reduces this critical viscosity to 10 5 10 8 p but this is still sufficiently large and is reached only near the maximum packing crystal fraction power law or bingham rheology of partial melts can exclude any turbulence already at 20 30 of crystal fraction we also show that the energetic criterion for the absolute suspension with e 1 coincides with the condition that the particle concentration gradient suppresses the turbulence

a chemical model for generating the sources of mare basalts combined equilibrium and fractional crystallization of the lunar magmasphere abstract it is generally considered that mare basalts were generated by the melting of a cumulate mantle formed in an early moon wide magma ocean or magmasphere however the nature and chemistry of this cumulate mantle and the logistics of its origin have remained elusive extensive studies of terrestrial layered mafic intrusions over the past sixty years have emphasized the imperfection of fractional crystallization and attendant crystal crystal and crystal liquid separation in a convecting magma chamber crystal liquid and crystal crystal separations were similarly inefficient during evolution of the lunar magma ocean lmo allowing for the trapping of interstitial liquid and entrainment of a small proportion of less dense plagioclase into the denser mafic cumulate mush indeed petrography of lunar highlands samples demonstrates this for anorthosites with 1 10 olivine the residual liquid after 80 90 crystallization was very evolved in fact kreepy and even in small proportions 1 5 would have a noticeable effect on the trace element chemistry of melts generated from these cumulates this trapped residual liquid would elevate total ree abundances in the cumulate pile while synchronously deepening the already negative eu anomaly essentially this trapped liquid will make the cumulate more fertile for melting to generate both kreep basalt and mare basalt magmas plagioclase entrained in the mafic cumulate pile adds an essential al component to the high ti basalt source and will moderate the requisite negative eu anomaly in the cumulate early in the evolution of the lunar mantle when the lmo still was largely liquid it is likely that vigorous convection was an important factor in crystallization such convection would allow crystals to remain suspended and in equilibrium with the lmo liquid for relatively long periods of time this extended period of equilibrium crystallization would then have been followed by fractional crystallization once plagioclase became a liquidus phase and began to float to form the lunar highlands crust previous authors have proposed a three component model for the evolution of high ti mare basalt source regions this model includes kreep early olivine rich high mg cumulates and late ilmeniterich low mg cumulates in various proportions however we propose a model for high ti basalt parent magmas which is in accord with studies of terrestrial layered intrusions this model for the high ti source includes trapped instantaneous residual liquid tirl 1 3 and entrainment of a small 2 5 proportion of plagioclase into the late stage cumulate pile in order to account for both the observed al compositions and trace element characteristics of high ti mare basalts melting of this relatively shallow ilmenite and clinopyroxene bearing late stage cumulate can generate high ti mare basalt magmas furthermore we are in agreement with other workers that only through a process of nonmodal melting will the high ti values for the parent magmas be realized large scale convective overturn of the cumulate pile and mixing of kreep with early and late stage cumulates is not required however localized overturn of the upper tenth of the cumulate pile is likely and in fact required to achieve an appropriate major element balance for the high ti mare basalt source region

rain shadow development during the growth of mountain ranges an atmospheric dynamics perspective 1 an idealized atmospheric model is used to explore the links between climate and topography in the development of orographic rain shadows during orogenesis the atmospheric dynamics theory of density stratified fluid flow over topography is used to interpret the results the controlling nondimensional parameter is nh u where n is the brunt vaisala frequency a measure of atmospheric stability h is the terrain relief and u is the initial horizontal wind speed rain shadow development is found to be a nonlinear and nonunique function of both topography and atmospheric state indicating that geological records of orographic aridity cannot be interpreted in terms of relief alone when upstream topography exceeds nh u 1 during surface uplift downstream orographic precipitation vanishes and downstream orographic cloud mass decreases by as much as 90 upstream blocking of air flow can generate a forward projecting rain shadow in which a relatively low ridge nh u 1 may be decoupled from the atmospheric flow by a zone of flow stagnation extending upstream of the high terrain such an effect may occur if the valley separating the two ranges is narrower than the length scale of flow stagnation in the model configuration used here lateral widening of a relatively low nh u 1 range increases downstream cloud mass by up to a factor of 3 these results help to refine interpretations of climate tectonic interactions in shaping the geological record of the sierra nevada and andes

a theoretical study of cold air damming abstract the dynamics of cold air damming are examined analytically with a two layer steady state model the upper layer is a warm and saturated cross mountain easterly or southeasterly onshore flow the lower layer is a cold mountain parallel northerly jet trapped on the windward eastern side of the mountain the interface between the two layers represents a coastal front a sloping inversion layer coupling the trapped cold dome with the warm onshore flow above through pressure continuity an analytical expression is obtained for the inviscid upper layer flow with hydrostatic and moist adiabatic approximations blackadar s pbl parameterization of eddy viscosity is used in the lower layer equations solutions for the mountain parallel jet and its associated secondary transverse circulation are obtained by expanding asymptotically upon a small parameter proportional to the square root of the inertial aspect ratio the ratio between the mountain height and the radius of inertial oscillation the geometr

effect of the andes cordillera on precipitation from a midlatitude cold front the effects of the andes cordillera the major mountain range in south america on precipitation patterns of baroclinic systems approaching from the southeast pacific remain largely unstudied this study focuses on a case in late may 2008 when an upper level trough and surface cold front produced widespread precipitation in central chile the primary goal was to analyze the physical mechanisms responsible for the structure and evolution of the precipitation weather research and forecasting wrf model simulations indicate that as an upper level trough approached central chile midtropospheric flow below 700 hpa was blocked by the high topography and deflected poleward in the form of a barrier jet this northerly jet had wind maxima in excess of 15 m s 21 was centered around 925 hpa and extended westward 200 km from the mountains it intersected the cold front which approached from the south near the coast thereby increasing convergence along the frontal surface slowing its equatorward progress and enhancing rainfall over central chile another separate region of heavy precipitation formed over the upwind slopes of the cordillera a trajectory analysis confirmed that the barrier jet moved low level parcels from their origin in the moist southeast pacific boundary layer to the coast when model topography was reduced to twenty percent of its original height the cold front advanced more rapidly to the northeast generated less precipitation in central chile between 338 and 368s and produced minimal orographic precipitation on the upwind andean slopes based on these findings the high topography appears responsible for not only orographic precipitation but also for substantially increasing precipitation totals over the central coast and valley