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

tektites apollo the crust and planets a life with trace elements stuart ross taylor msc university of new zealand phd indiana university scd university of oxford faa ac always called ross grew up on a farm near ashburton new zealand ross has worked on a wide variety of topics in trace element geochemistry including the composition and evolution of the moon the continental crust tektites impact glasses and island arc rocks in 1969 he carried out the first chemical analysis of the first returned lunar sample at nasa in houston he has published 10 books and 240 papers in scientific journals he was awarded the v m goldschmidt award of the geochemical society in 1993 in 1994 he was elected a foreign associate of the national academy of sciences in 1998 he was awarded the leonard medal of the meteoritical society in 2002 the bucher medal of the american geophysical union and in 2012 the shoemaker distinguished lunar scientist medal of the nasa lunar science institute asteroid 5670 is named rosstaylor

isotopic fractionation of cu in tektites tektites are terrestrial natural glasses of up to a few centimeters in size that were produced during hypervelocity impacts on the earth s surface it is well established that the chemical and isotopic composition of tektites is generally identical to that of the upper terrestrial continental crust tektites typically have very low water content which has generally been explained by volatilization at high temperature however the exact mechanism is still debated because volatilization can fractionate isotopes comparing the isotopic composition of volatile elements in tektites with those of their source rocks may help to understand the physical conditions during tektite formation interestingly volatile chalcophile elements e g cd and zn seem to be the only elements for which isotopic fractionation is known so far in tektites here we extend this study to cu another volatile chalcophile element we have measured the cu isotopic composition for 20 tektite samples from the four known different strewn fields all of the tektites except the muong nong types are enriched in the heavy isotopes of cu 1 98 delta 61 cu 6 99 in comparison to the terrestrial crust delta 65 cu approximate to 0 with no clear distinction between the different groups the muong nong type tektites and a libyan desert glass sample are not fractionated delta 65 cu approximate to 0 in comparison to the terrestrial crust to refine the cu isotopic composition of the terrestrial crust we also present data for three geological reference materials delta 65 cu approximate to 0 an increase of delta 65 cu with decreasing cu abundance probably reflects that the isotopic fractionation occurred by evaporation during heating a simple rayleigh distillation cannot explain the cu isotopic data and we suggest that the isotopic fractionation is governed by a diffusion limited regime copper is isotopically more fractionated than the more volatile element zn delta 66 64 zn up to 2 49 parts per thousand this difference of behavior between cu and zn is predicted in a diffusion limited regime where the magnitude of the isotopic fractionation is regulated by the competition between the evaporative flux and the diffusive flux at the diffusion boundary layer due to the difference of ionic charge in silicates zn 2 vs cu cu has a diffusion coefficient that is larger than that of zn by at least two orders of magnitude therefore the larger isotopic fractionation in cu than in zn in tektites is due to the significant difference in their respective chemical diffusivity c 2009 elsevier ltd all rights reserved

the proto earth as a significant source of lunar material geochemical evidence continues to challenge giant impact models which predict that the moon formed from both proto earth and impactor material analyses of lunar samples reveal isotopic homogeneity in titanium a highly refractory element suggesting lunar material was derived predominantly from the mantle of the proto earth

quantification of tidal asymmetry and its nonstationary variations tidal wave deformation and tidal asymmetry widely occur in tidal estuaries and lagoons tidal asymmetry has been intensively studied because of its controlling role on residual sediment transport and large scale morphological evolution there are several methods available to characterize tidal asymmetry prompting the need for an overview of their applicability and shortcomings in this work we provide a brief review and evaluation of two methods namely the harmonic method and the statistical method the latter comprises several statistical measures that estimate the probability density function and various forms of skewness we find that both the harmonic and statistical methods are effective and have complementary advantages the harmonic method is applicable to predominantly semidiurnal or diurnal regimes while the statistical methods can be used in mixed tidal regimes assisted by harmonic data a modified skewness measure can isolate the contribution of different tidal interactions on net tidal asymmetry and also reveal its subtidal variations the application of the skewness measure to nonstationary river tides reveals stronger tidal asymmetry during spring tides than neap tides and the nonlinear effects of river discharges on tidal asymmetry in the upper and lower regions of long estuaries

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

tidal distortions and flood dominance at five small tidal inlets in southern maine maximum and mean flood current velocities exceeded ebb current velocities by an average of more than 20 cm s 1 at five small inlets along the southern coast of maine distortion of the tidal wave as it interacts with these shallow inlets such that the rising tide duration averages 3 22 h less than the falling tide duration may be the cause of flood current dominance at these inlets tide records from three locations at ogunquit inlet located along the southern coast of maine show that the 29 day average tide duration asymmetry increases from a rising tide that is 0 07 h longer than the falling tide for the offshore record to a rising tide that is 2 15 and 5 15 h shorter than the falling tide for the inlet throat and bay records respectively previous field studies and numerical models of tidal asymmetry have not examined tidal distortion in very shallow inlets where the channels shoal to depths shallower than the forcing tide amplitude at the inlets investigated in this paper channels are shallower than the ocean tide amplitude by an average of 30 cm a model is presented that explains how the shallow inlet bathymetry truncates the ocean tide and produces an inlet tide characterized by an extended falling tide and a shortened rising tide duration the dominance of flood tidal currents at these inlets produces net landward sediment transport

lunar apatite with terrestrial volatile abundances the moon is thought to be depleted relative to the earth in volatile elements such as h cl and the alkalis nevertheless evidence for lunar explosive volcanism has been used to infer that some lunar magmas exsolved a co rich and co 2 rich vapour phase before or during eruption although there is also evidence for other volatile species on glass spherules until recently there had been no unambiguous reports of indigenous h in lunar rocks here we report quantitative ion microprobe measurements of late stage apatite from lunar basalt 14053 that document concentrations of h cl and s that are indistinguishable from apatites in common terrestrial igneous rocks these volatile contents could reflect post magmatic metamorphic volatile addition or growth from a late stage interstitial sulphide saturated melt that contained 1 600 parts per million h 2o and 3 500 parts per million cl both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable terrestrial materials one possible implication is that portions of the lunar mantle or crust are more volatile rich than previously thought

the moon re examined abstract recent geochemical and geophysical data from the moon enable a revision of earlier interpretations regarding lunar origin structure and bulk composition earth and moon show many similarities among their isotopic compositions but they have evolved in totally dissimilar ways probably related to the deficiency of water in the moon as well as the vast differences in size and internal pressure although some global geochemical trends such as volatile depletion based on k u ratios have been established current lunar samples come from differentiated regions making the establishment of a bulk composition more reliant on bulk geophysical properties or isotopic similarities although it remains unclear how the latter relate to whole moon composition the lack of fractionation effects among the refractory and super refractory elements indicates that the proto lunar material seems unlikely to have been vaporized while the depletion of volatile elements may place lower limits on proto lunar temperatures the apparent lack of geochemical evidence of an impacting body enables other possible impactors such as comets to be considered

major lunar crustal terranes surface expressions and crust mantle origins in light of global remotely sensed data the igneous crust of the moon can no longer be viewed as a simple globally stratified cumulus structure composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual melt kreep sandwich horizon near the base of the lower crust instead global geochemical information derived from clementine multispectral data and lunar prospector gamma ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique 1 the procellarum kreep terrane pkt 2 the feldspathic high lands terrane fht and 3 the south pole aitken terrane spat the pkt is a mafic province coincident with the largely resurfaced area in the procellarum imbrium region whose petrogenesis relates to the early differentiation of the moon here some 40 of the th in the moon s crust is concentrated into a region that constitutes only about 10 of the crustal volume this concentration of th average 5 ppm and by implication the other heat producing elements u and k led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust lower crustal materials within the pkt likely interacted with underlying mantle materials to produce hybrid magmatism leading to the magnesian suite of lunar rocks and possibly kreep basalt although rare in the apollo sample collection widespread mare volcanic rocks having substantial th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources the fht is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation basin impacts into this region do not excavate significantly more mafic material suggesting a thickness of tens of kilometers of anorthositic crust the feldspathic lunar meteorites may represent samples from the anorthositic central region of the fht ejecta from deep penetrating basin impacts outside of the central anorthositic region however indicate an increasingly mafic composition with depth the spat a mafic anomaly of great magnitude may include material of the upper mantle as well as lower crust thus it is designated a separate terrane whether the spa basin impact simply uncovered lower crust such as we infer for the fht remains to be determined

compositional maps of saturn s moon phoebe from imaging spectroscopy the origin of phoebe which is the outermost large satellite of saturn is of particular interest because its inclined retrograde orbit suggests that it was gravitationally captured by saturn having accreted outside the region of the solar nebula in which saturn formed by contrast saturn s regular satellites with prograde low inclination circular orbits probably accreted within the sub nebula in which saturn itself formed here we report imaging spectroscopy of phoebe resulting from the cassini huygens spacecraft encounter on 11 june 2004 we mapped ferrous iron bearing minerals bound water trapped co2 probable phyllosilicates organics nitriles and cyanide compounds detection of these compounds on phoebe makes it one of the most compositionally diverse objects yet observed in our solar system it is likely that phoebe s surface contains primitive materials from the outer solar system indicating a surface of cometary origin

tidal asymmetry in estuaries with mixed semidiurnal diurnal tides 1 tidal asymmetry in estuaries with mixed mainly semidiurnal tides arises from both the interaction of principal tides and the higher harmonics generated by distortions within the estuary the duration asymmetry in rise and fall of water level caused by principal tides on the west coast of the continental united states is ebb dominant and so the tide entering estuaries is also ebb dominant prior to any internal distortions within the estuary the interaction of higher harmonics with principal constituents either augments or cancels the duration asymmetry in the principal tides in estuaries where tidal elevation and velocity phase are near quadrature 90 out of phase the duration asymmetry in tidal elevation leads to asymmetries in tidal current magnitude asymmetry can be conveniently quantified in terms of the sample skewness 1 the normalized third sample moment about the mean an analytic approximation to the skewness shows that traditional metrics of asymmetry namely the ratio of constituent amplitudes and the relative constituent phase difference arise from calculating the third sample moment observations from three california estuaries of different morphologies are presented as an illustration of how skewness can be used to quantify asymmetry in real systems as in semidiurnal systems morphology is a good predictor of whether higher harmonics engender ebb dominance or flood dominance however asymmetry imposed by principal tides at the mouth must first be overcome and so there is a spatial evolution in the total asymmetry quantifying observations via skewness should be considered in addition to traditional metrics in estuaries with mixed tides

lunar regolith can allow the synthesis of cement materials with near zero water consumption abstract with the continuous development of science and technology and the human understanding of the moon many scientists have planned the creation of a space station on the moon using lunar building materials environmental factors mainly include large temperature differentials and the presence of a hard vacuum on the surface of the moon is a huge challenge for the performance of lunar building materials geopolymer materials have the following properties approximately zero water consumption resistance to high and low temperature cycling vacuum stability and good mechanical properties additionally they meet most of the requirements for use in the lunar environment here we present a potential lunar cement material that was fabricated using volcanic ash and sodium hydroxide solution as activator based on geopolymer technology the compressive strengths of the volcanic ash geopolymer specimens processed for 24 h under vacuum conditions and 30 freeze thaw cycles in liquid nitrogen are 45 53 and 44 95 mpa respectively additionally 98 61 of water could be recycled in consistence with the water recycling simulated lunar environment in the lab although volcanic ash is not equivalent to the lunar soil we speculate that the alkali activation of lunar soil could be very close to that of volcanic ash because of their similar chemical and mineralogical composition in summary this study provides a feasible approach for the development of near zero water consumption lunar cement materials based on geopolymer technology

hydroxyl oh production on airless planetary bodies evidence from h d ion beam experiments abstract the hypothesis that bombardment of lunar soil with solar wind protons might form hydroxyl oh and perhaps hoh has been tested by experiments with apollo 16 highlands and apollo 17 mare soils pre dried soils 500 c were bombarded with 1 1 kev protons and deuterons and provide unambiguous evidence for the formation of oh or od in both samples this hypothesis further predicts the formation of hydroxyl oh on other airless planetary asteroidal bodies with a sufficient solar wind flux deuteron implantation of unaltered lunar soils and a heat treated plagioclase specimen cause simultaneous oh depletion and od formation ion bombardment of lunar soils simulates the dynamic process of hydroxyl formation and may also deplete intrinsic oh thereby effectively contributing to the day night diurnal variability of oh reported by sunshine et al 2009 our results emphasize the need to use lunar soils with space weathered exteriors in laboratory simulations of the solar wind infrared spectra of hydrogen ion beam implanted soils are similar to spectra obtained at relab brown univ and to those observed by remote sensing confirming the solar wind hypothesis

magnesium isotopic composition of the moon abstract the mg isotopic compositions of 47 well characterized lunar samples including mare basalts highland rocks regolith breccias and mare and highland soils were measured to address the behavior of mg isotopes during lunar magmatic differentiation constrain the mg isotopic composition of the moon and evaluate the degree of mg isotopic fractionation between planetary bodies the 26 mg values range from 0 61 0 03 to 0 02 0 06 in 22 mare basalts from 0 34 0 04 to 0 18 0 06 in 3 highland rocks from 0 33 0 05 to 0 14 0 08 in 7 regolith breccias from 0 23 0 05 to 0 14 0 07 in 6 highland soils and from 0 41 0 05 to 0 20 0 09 in 9 mare soils the limited mg isotopic variation among bulk mare and highland soils and regolith breccias indicates negligible mg isotope fractionation by lunar surface processes by contrast the large mg isotopic fractionation between low ti and high ti basalts suggests the source heterogeneity produced during fractional crystallization of the lunar magma ocean with ilmenite having lighter mg isotopic compositions than olivine and pyroxene overall the moon has a weighted average mg isotopic composition 26 mg 0 26 0 16 indistinguishable from the earth 26 mg 0 25 0 07 and chondrites 26 mg 0 28 0 06 suggesting homogeneous mg isotopic distribution in the solar system and the lack of mg isotope fractionation during the moon forming giant impact

variscan accretionary complex of northwest iberia terrane correlation and succession of tectonothermal events the allochthonous terranes of northwest iberia can be correlated with specific paleogeographic realms of the continental masses and intervening oceans involved in the variscan collision assuming that the existing ophiolites represent the suture formed by the closure of the rheic ocean the units in the footwall to the suture correspond to the outer edge of the gondwana continental margin and the units in the hanging wall are interpreted as fragments of the conjugate margin represented by the meguma terrane this correlation establishes a precise link between circum atlantic terranes and makes it possible to draw a relatively simple scenario of the successive tectonothermal events recorded following the amalgamation of avalon to laurentia the remaining outboard terranes underwent a progressive accretion to this continent that ended with the collision between laurentia and gondwana

the role of river flow and tidal asymmetry on 1 d estuarine morphodynamics numerous research efforts have been devoted to understanding estuarine morphodynamics under tidal forcing however the impact of river discharge on estuarine morphodynamics is insufficiently examined inspired by the yangtze estuary this work explores the morphodynamic impact of river discharge in a 560 km long tidal basin based on a 1 d model delft3d the model considers total load sediment transport and employs a morphodynamic updating scheme to achieve long term morphodynamic evolution we analyze the role of stokes drift tidal asymmetry and river discharge in generating tidal residual sediment transport model results suggest that morphodynamic equilibrium is approached within millennia by vanishing spatial gradients of tidal residual sediment transport we find that the interaction between ebb directed stokes return flow river flow with tides is an important mechanism that flushes river supplied sediment seaward increasing river discharge does not induce continuously eroded or accreted equilibrium bed profiles because of the balance between riverine sediment supply and sediment flushing to the sea an intermediate threshold river discharge can be defined which leads to a deepest equilibrium bed profile as a result the shape concavity or convexity of the equilibrium bed profiles will adapt with the magnitude of river discharge overall this study reveals the significant role of river discharge in controlling estuarine morphodynamics by supplying sediment and reinforcing ebb directed residual sediment transport

a young solidification age for the lunar magma ocean abstract the time at which the lunar magma ocean solidified can be determined from the lu hf isotope systematics of lunar rocks derived from magma sources that formed during crystallization of the lunar magma ocean the final magma ocean crystallization product termed urkreep is enriched in incompatible elements including k ree and p we have determined the initial hf isotopic compositions of four samples two kreep basalts and two mg suite norites the incompatible trace element compositions of these samples are controlled by an urkreep component and therefore the initial hf isotopic compositions of these samples represent the hf isotopic evolution of urkreep in order to correct the effects of neutron irradiation on the hf isotopic compositions of these samples we have developed a model that uses the stable hf and sm isotopic compositions measured on an irradiated sample to determine and correct for the thermal and epithermal neutron fluence that has modified the hf isotopic composition of the sample we use our corrected results to calculate a 176 lu 176 hf urkreep model age of 4353 37 ma and the 176 lu 177 hf of urkreep to be 0 0153 0 0033 the lu hf model age is concordant with the re calculated sm nd urkreep model age of 4389 45 ma and we take the average of these ages 4368 29 ma to represent the time at which urkreep formed this age is concordant with the age of the most reliably dated ferroan noritic anorthosite as well as 142 nd model ages for the formation or re equilibration of mare basalt sources taken together these ages indicate that the moon experienced a widespread large scale magmatic event around 4370 ma most plausibly attributed to solidification of the lunar magma ocean

highly siderophile element constraints on accretion and differentiation of the earth moon system a new combined rhenium osmium and platinum group element data set for basalts from the moon establishes that the basalts have uniformly low abundances of highly siderophile elements the data set indicates a lunar mantle with long term chondritic highly siderophile element ratios but with absolute abundances that are over 20 times lower than those in earth s mantle the results are consistent with silicate metal equilibrium during a giant impact and core formation in both bodies followed by post core formation late accretion that replenished their mantles with highly siderophile elements the lunar mantle experienced late accretion that was similar in composition to that of earth but volumetrically less than approximately 0 02 lunar mass and terminated earlier than for earth

correlated δ 18 o and ti in lunar zircons a terrestrial perspective for magma temperatures and water content on the moon zircon grains were separated from lunar regolith and rocks returned from four apollo landing sites and analyzed in situ by secondary ion mass spectrometry many regolith zircons preserve magmatic 18o and trace element compositions and although out of petrologic context represent a relatively unexplored resource for study of the moon and possibly other bodies in the solar system the combination of oxygen isotope ratios and ti provides a unique geochemical signature that identifies zircons from the moon the oxygen isotope ratios of lunar zircons are remarkably constant and unexpectedly higher in 18o 5 61 0 07 vsmow than zircons from earth s oceanic crust 5 20 0 03 even though mare basalt whole rock samples are nearly the same in 18o as oceanic basalts on earth 5 6 thus the average fractionation of oxygen isotopes between primitive basalt and zircon is smaller on the moon 18o wr zrc 0 08 0 09 than on earth 0 37 0 04 the smaller fractionations on the moon suggest higher temperatures of zircon crystallization in lunar magmas and are consistent with higher ti in lunar zircons phase equilibria estimates also indicate high temperatures for lunar magmas but not specifically for evolved zircon forming melts if the solidus temperature of a given magma is a function of its water content then so is the crystallization temperature of any zircon forming in that melt the systematic nature of o and ti data for lunar zircons suggests a model based on the following observations many of the analyzed lunar zircons are likely from k rare earth elements p kreep zr rich magmas zircon does not saturate in normal mafic magmas igneous zircons in mafic rocks are typically late and formed in the last most evolved portion of melts even if initial bulk water content is moderately low the late zircon forming melt can concentrate water locally in general water lowers crystallization temperatures in which case late igneous zircon can form at significantly lower temperatures than the solidus inferred for a bulk rock composition although lunar basalts could readily lose h2 to space during eruption lowering water fugacity the morphology large size and presence in plutonic rocks suggest that many zircons crystallized at depths that retarded degassing in this case the crystallization temperatures of zircons are a sensitive monitor of the water content of the parental magma as well as the evolved zircon forming melt if the smaller 18o zircon mare basalt values reported here are characteristic of the moon then that would suggest that even highly evolved zircon forming magmas on the moon crystallized at higher temperature than similar magmas on earth and that magmas though not necessarily water free were generally drier on the moon

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

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

chronological evidence that the moon is either young or did not have a global magma ocean a new age determination for a moon rock collected close to the site of the apollo 16 lander has yielded a surprisingly young age of around 4 360 million years this age would require either that the moon solidified some 200 million years after the formation of the solar system significantly later than is assumed by most lunar formation models or that the long held theory that the moon once had a primordial global magma ocean is flawed in the latter case much of the lunar crust could have been produced by non magma ocean processes such as serial magmatism chemical evolution of planetary bodies ranging from asteroids to the large rocky planets is thought to begin with differentiation through solidification of magma oceans many hundreds of kilometres in depth1 2 3 the earth s moon is the archetypical example of this type of differentiation evidence for a lunar magma ocean is derived largely from the widespread distribution compositional and mineralogical characteristics and ancient ages inferred for the ferroan anorthosite fan suite of lunar crustal rocks the fans are considered to be primary lunar flotation cumulate crust that crystallized in the latter stages of magma ocean solidification according to this theory fans represent the oldest lunar crustal rock type2 3 4 attempts to date this rock suite have yielded ambiguous results however because individual isochron measurements are typically incompatible with the geochemical make up of the samples and have not been confirmed by additional isotopic systems5 6 7 8 9 by making improvements to the standard isotopic techniques we report here the age of crystallization of fan 60025 using the 207pb 206pb 147sm 143nd and 146sm 142nd isotopic systems to be 4 360 3 million years this extraordinarily young age requires that either the moon solidified significantly later than most previous estimates or the long held assumption that fans are flotation cumulates of a primordial magma ocean is incorrect if the latter is correct then much of the lunar crust may have been produced by non magma ocean processes such as serial magmatism10

the titanium contents of lunar mare basalts lunar mare basalt sample data suggest that there is a bimodal distribution of tio2 concentrations using a refined technique for remote determination of tio2 we find that the maria actually vary continuously from low to high values the reason for the discrepancy is that the nine lunar sample return missions were not situated near intermediate basalt regions moreover maria with 2 4 wt tio2 are most abundant and abundance decreases with increasing tio2 maria surfaces with tio2 5 wt constitute only 20 of the maria although impact mixing of basalts with differing ti concentrations may smear out the distribution and decrease the abundance of high ti basalts the distribution of basalt ti contents probably reflects both the relative abundances of ilmenite free and ilmenite bearing mantle sources this distribution is consistent with models of the formation of mare source regions as cumulates from the lunar magma ocean

high pressure micro inclusions and development of an inverted metamorphic gradient in the santiago schists ordenes complex nw iberian massif spain evidence of subduction and syncollisional decompression the santiago schists are located in the basal unit of the ordenes complex one of the allochthonous complexes outcropping in the inner part of the hercynian belt in the north west of the iberian peninsula their tectonothermal evolution is characterized by the development of an eo hercynian metamorphic episode c 374 ma of high p low to intermediate t the mineral assemblage of the high p episode is preserved as a very thin si s1 foliation included in albite porphyroblasts being composed of albite garnet i white mica 1 chlorite 1 epidote quartz rutile ilmenite the equilibrium conditions for this mineral assemblage have been estimated by means of different thermobarometers at 495 10 c and 14 7 0 7 kbar probably minimum pressure the later evolution syn d2 of the schists defines a decompressive and slightly prograde p t path which reached its thermal peak at c 525 10 c and 7 kbar decompression of the unit occurred contemporaneously with an inversion of the metamorphic gradient so that the zones of garnet ii biotite with an upper subzone with chloritoid and staurolite developed from bottom to top of the formation the estimated p t path for the santiago schists suggests that the basal unit probably a fragment of the gondwana continental margin was uplifted immediately after its subduction at the beginning of the hercynian orogeny it also suggests that the greater part of the unroofing history of the unit took place in a context of ductile extension probably related to the continued subduction of the gondwana continental margin and the contemporaneous development of compensatory extension above it the inverted metamorphic gradient seems related to conductive heat transferred from a zone of the mantle wedge above the subducted continental margin when it came into contact with the upper parts of the schists along a detachment probably of extensional character the general metamorphic evolution of the santiago schists with the development of high p assemblages with garnet prior to decompressive and prograde parageneses with biotite is unusual in the context of the european hercynian belt and shows a close similarity to the tectonothermal evolution of several high p low to intermediate t circum pacific belts

sr stable isotope composition of earth the moon mars vesta and meteorites abstract high precision stable sr isotopic variations 88 sr 86 sr are reported in a variety of terrestrial samples martian and lunar meteorites hed undifferentiated primitive meteorites chondrules and refractory inclusions almost all the whole rock samples are isotopically indistinguishable at a 50 parts per million ppm level the exceptions are cv and co chondrites which are isotopically light and for which we believe that their isotopic composition is controlled by the proportion of refractory material five separated chondrules and one refractory inclusion from allende are isotopically light with 88 86 sr fractionations up to 1 73 whereas the matrix is enriched in the heavy isotopes 88 86 sr 0 66 the depletion in heavy isotopes observed in chondrules and refractory inclusions could be attributed to the condensation of a material already depleted in sr however in that case more than 60 of the original material would be unaccounted we propose instead that isotopic fractionation by electromagnetic sorting of ionized heavy sr from neutral sr in the early solar system for the origin of the fractionation observed in refractory inclusions and redistribution of sr by aqueous alteration for the origin of the fractionation observed in chondrules and matrix we conclude that cv and co chondrites are not the primary building blocks for earth and mars

the fate of moderately volatile elements in impact events lithium connection between the ries sediments and central european tektites lithium abundances and isotope compositions are presented for a suite of sediments from the surroundings of the ries impact structure paralleled by new li data for central european tektites moldavites from several substrewn fields south bohemia moravia cheb basin lusatia including a specimen from the newly discovered substrewn field in poland the data set was supplemented by three clay fractions isolated from sedimentary samples moldavites measured in this study show a very narrow range in 7li values 0 6 to 0 3 relative to l svec and li contents 23 9 48 1 ppm this contrasts with sediments from the ries area which show remarkable range in li isotope compositions from 6 9 to 13 4 and li contents 0 6 256 ppm the osm sediments which based on chemical similarity formed the major part of moldavites show a range in 7li values from 2 0 to 7 9 and li contents from 5 8 to 78 9 ppm therefore the formation of moldavites was apparently accompanied by large scale mixing paralleled by chemical and isotope homogenization of their parent matter the proposed li mixing model indicates that sands clayey sediments and low volumes of carbonates are the major components for tektite formation whereas residual paleokarst sediments could have been a minor but important component for a subset of moldavites striking homogenization of li in tektites combined with limited li loss during impacts may suggest that moderately volatile elements are not scavenged and isotopically fractionated during large scale collisions which is consistent with recent models in general whether homogenization of bodies with distinct li isotope systematics takes place or collision of bodies with similar li systematics operates cannot be resolved at present stage but li isotope homogeneity of solar system planets and asteroidal bodies tentatively implies the latter

a 4 2 billion year old impact basin on the moon u pb dating of zirconolite and apatite in lunar melt rock 67955 abstract a sharp rise in the flux of asteroid size bodies traversing the inner solar system at 3 9 ga has become a central tenet of recent models describing planetary dynamics and the potential habitability of early terrestrial environments the prevalence of 3 9 ga crystallization ages for lunar impact melt breccias and u pb isotopic compositions of lunar crustal rocks provide the primary evidence for a short lived cataclysmic episode of late heavy bombardment at that time here we report u pb isotopic compositions of zirconolite and apatite in coarse grained lunar melt rock 67955 measured by ion microprobe that date a basin scale impact melting event on the moon at 4 22 0 01 ga followed by entrainment within lower grade ejecta from a younger basin approximately 300 million yr later significant impacts prior to 3 9 ga are also recorded by lunar zircons although the magnitudes of those events are difficult to establish other isotopic evidence such as 40 ar 39 ar ages of granulitic lunar breccias regolith fragments and clasts extracted from fragmental breccias and re os isotopic compositions of lunar metal is also suggestive of impact related thermal events in the lunar crust during the period 4 1 4 3 ga we conclude that numerous large impactors hit the moon prior to the canonical 3 9 ga cataclysm that some of those pre cataclysm impacts were similar in size to the younger lunar basins and that the oldest preserved lunar basins are likely to be significantly older than 3 9 ga this provides sample based support for dynamical models capable of producing older basins on the moon and discrete populations of impactors an extended period of basin formation implies a less intense cataclysm at 3 9 ga and therefore a better opportunity for preservation of early habitable niches and hadean crust on the earth a diminished cataclysm at 3 9 ga suggests that the similarity in the age of the oldest terrestrial continental crust with the canonical lunar cataclysm is likely to be coincidental with no genetic significance

zinc isotopic evidence for the origin of the moon lunar magmatic rocks are shown to be enriched in the heavy isotopes of zinc and to have lower zinc concentrations than terrestrial or martian igneous rocks these variations represent the large scale evaporation of zinc most probably in the aftermath of the moon forming giant impact event the heavily favoured theory for the origin of the earth moon system is a giant impact between the proto earth and a mars sized body such a cataclysmic event would have left its mark on the isotopic composition of the moon because light isotopes evaporate more readily than heavier ones zinc in particular is a powerful indicator of the volatile histories of planets it undergoes strong isotopic fractionation in planetary rocks but is hardly fractionated following volcanic activity on earth this study compares high precision zinc isotopic data for lunar basalts martian meteorites and terrestrial igneous rocks and finds that lunar magmatic rocks are enriched in the heavy isotopes of zinc and have lower zinc concentrations than terrestrial or martian samples the authors conclude that these variations are the result of large scale evaporation of zinc in the aftermath of the moon forming giant impact event volatile elements have a fundamental role in the evolution of planets but how budgets of volatiles were set in planets and the nature and extent of volatile depletion of planetary bodies during the earliest stages of solar system formation remain poorly understood1 2 the moon is considered to be volatile depleted and so it has been predicted that volatile loss should have fractionated stable isotopes of moderately volatile elements3 one such element zinc exhibits strong isotopic fractionation during volatilization in planetary rocks4 5 but is hardly fractionated during terrestrial igneous processes6 making it a powerful tracer of the volatile histories of planets here we present high precision zinc isotopic and abundance data which show that lunar magmatic rocks are enriched in the heavy isotopes of zinc and have lower zinc concentrations than terrestrial or martian igneous rocks conversely earth and mars have broadly chondritic zinc isotopic compositions we show that these variations represent large scale evaporation of zinc most probably in the aftermath of the moon forming event rather than small scale evaporation processes during volcanism our results therefore represent evidence for volatile depletion of the moon through evaporation and are consistent with a giant impact origin for the earth and moon

the regolith properties of the chang e 5 landing region and the ground drilling experiments using lunar regolith simulants abstract the chang e 5 ce 5 mission is china s first lunar sample return mission the rumker region in northern oceanus procellarum was selected as the landing area ce 5 will automatically sample 2 kg of lunar samples from the surface and subsurface previous studies focused more on the geological background of the landing region however the lunar regolith properties also have a significant influence on the mission especially drilling and thus should be studied and constrained in this research we analyzed the lunar regolith properties of the ce 5 landing region first using remote sensing measurements the western maria and eastern maria in the landing region are both covered by very low ti to low ti basaltic regolith the western mare regolith with longer exposure to space weathering is more mature finer and thicker than the eastern mare regolith cug series lunar regolith simulants were then produced based on our analysis physically and chemically of the regolith properties of ce 5 landing region and compared to apollo soils finally the lunar simulants were used to perform ground drilling experiments to support the drilling of the ce 5 mission in a fixed rotation speed 120 rpm feed speed 120 mm min and total drilling depth 1 m 274 291 and 346 g of lunar simulants were cored on simulants mixture 1 mixture 2 and mixture 3 respectively our experiments suggest that it is easier to drill and core finer and looser lunar regolith in this case the western mare regolith is easier for drilling than the eastern mare regolith however samples from the eastern young maria em3 em4 are scientifically more meaningful we propose that landing on and drilling in a smooth and mature area in unit em4 should be the highest priority for the ce 5 mission this can be accomplished by careful landing site selection precise landing and optimized drilling control

forming a moon with an earth like composition via a giant impact in the giant impact theory the moon formed from debris ejected into an earth orbiting disk by the collision of a large planet with the early earth prior impact simulations predict that much of the disk material originates from the colliding planet however earth and the moon have essentially identical oxygen isotope compositions this has been a challenge for the impact theory because the impactor s composition would have likely differed from that of earth we simulated impacts involving larger impactors than previously considered we show that these can produce a disk with the same composition as the planet s mantle consistent with earth moon compositional similarities such impacts require subsequent removal of angular momentum from the earth moon system through a resonance with the sun as recently proposed

river flow controls on tides and tide mean water level profiles in a tidal freshwater river 1 tidal rivers feature oscillatory and steady gradients in the water surface controlled by interactions between river flow and tides the river discharge attenuates the tidal motion and tidal motion increases tidal mean friction in the river which may act as a barrier to the river discharge time series of tidal water level amplitudes at five gauge stations along the river mahakam in indonesia and tidal flow velocity amplitudes at a discharge monitoring station were obtained applying wavelet analysis temporal variations in tidal damping coefficients for quaterdiurnal semidiurnal and diurnal tidal species were quantified from the observed amplitude profiles the analysis shows that tidal damping during the rising limb of a discharge wave differs from damping during the falling limb wavelet cross correlations between surface levels yielded empirical estimates of wave numbers an empirical relation between tidal damping and river flow is derived to describe subtidal bottom friction along an idealized tidal river resembling the mahakam the subtidal friction is decomposed into contributions from the river flow only from river tide interaction and from tidal asymmetry even for high river flow and low tidal velocity river flow enhances friction attributed to river tide interaction causing subtidal water level setup a simple multilinear regression model using subtidal bottom friction is employed to predict subtidal water levels at locations upstream with a relatively good agreement between predictions and observations the explicit expression shows the nonlinear dependence of subtidal friction on river flow velocity explaining the complex behavior of tidal mean surface level profiles

chemical fractionation in the silicate vapor atmosphere of the earth despite its importance to questions of lunar origin the chemical composition of the moon is not precisely known in recent years however the isotopic composition of lunar samples has been determined to high precision and found to be indistinguishable from the terrestrial mantle despite widespread isotopic heterogeneity in the solar system in the context of the giant impact hypothesis this level of isotopic homogeneity can evolve if the proto lunar disk and post impact earth undergo turbulent mixing into a single uniform reservoir while the system is extensively molten and partially vaporized in the absence of liquid vapor separation such a model leads to the lunar inheritance of the chemical composition of the terrestrial magma ocean hence the turbulent mixing model raises the question of how chemical differences arose between the silicate earth and moon here we explore the consequences of liquid vapor separation in one of the settings relevant to the lunar composition the silicate vapor atmosphere of the post giant impact earth we use a model atmosphere to quantify the extent to which rainout can generate chemical differences by enriching the upper atmosphere in the vapor and show that plausible parameters can generate the postulated enhancement in the feo mgo ratio of the silicate moon relative to the earth s mantle moreover we show that liquid vapor separation also generates measurable mass dependent isotopic offsets between the silicate earth and moon and that precise silicon isotope measurements can be used to constrain the degree of chemical fractionation during this earliest period of lunar history an approach of this kind has the potential to resolve long standing questions on the lunar chemical composition

osmium isotope and highly siderophile element systematics of the lunar crust abstract coupled 187os 188os and highly siderophile element hse os ir ru pt pd and re abundance data are reported for pristine lunar crustal rocks 60025 62255 65315 ferroan anorthosites fan and 76535 78235 77215 and a norite clast in 15455 magnesian suite rocks mgs osmium isotopes permit more refined discrimination than previously possible of samples that have been contaminated by meteoritic additions and the new results show that some rocks previously identified as pristine contain meteorite derived hse low hse abundances in fan and mgs rocks are consistent with derivation from a strongly hse depleted lunar mantle at the time of formation the lunar floatation crust represented by fan had 1 4 0 3 pg g 1 os 1 5 0 6 pg g 1 ir 6 8 2 7 pg g 1 ru 16 15 pg g 1 pt 33 30 pg g 1 pd and 0 29 0 10 pg g 1 re 0 00002 ci and re os ratios that were modestly elevated 187re 188os 0 6 to 1 7 relative to ci chondrites mgs samples are on average characterised by more elevated hse abundances 0 00007 ci compared with fan this either reflects contrasting mantle source hse characteristics of fan and mgs rocks or different mantle crust hse fractionation behaviour during production of these lithologies previous studies of lunar impact melt rocks have identified possible elevated ru and pd in lunar crustal target rocks the new results provide no supporting evidence for such enrichments if maximum estimates for hse in the lunar mantle are compared with fan and mgs averages crust mantle concentration ratios d values must be 0 3 such d values are broadly similar to those estimated for partitioning between the terrestrial crust and upper mantle with the notable exception of re given the presumably completely different mode of origin for the primary lunar floatation crust and tertiary terrestrial continental crust the potential similarities in crust mantle hse partitioning for the earth and moon are somewhat surprising low hse abundances in the lunar crust coupled with estimates of hse concentrations in the lunar mantle implies there may be a missing component of late accreted materials as much as 95 to the moon if the earth moon mass flux estimates are correct and terrestrial mantle hse abundances were established by late accretion

isotopic composition of zinc copper and iron in lunar samples abstract we determined by icp ms the concentrations and isotopic ratios of fe cu and zn in the ti rich lunar basalt 74275 in the lunar orange glass 74220 and in up to 10 lunar soils namely 14163 15231 64501 66041 68841 69941 70011 72501 75081 and 76501 two analyses of zinc in lunar basalt 74275 give 66 zn 0 17 and 0 75 values within the range of those measured in terrestrial basalts copper in lunar basalt 74275 has 65 cu 1 4 which is isotopically heavier than values observed in terrestrial basalts in the orange glass we measured 56 fe 0 24 65 cu 0 42 and 66 zn 3 6 these values of are more negative than those obtained for 74275 and for typical lunar basalts but for cu comparable to those observed in terrestrial sulfides and meteorites in lunar soils we found 0 11 56 fe 0 51 2 6 65 cu 4 5 and 2 2 66 zn 6 4 insofar as we can generalize from a small sample set s fe cu zn and cd show similar trends in isotopic fractionation on the moon lunar basalts have nearly terrestrial isotopic ratios relative to the lunar basalt 74275 the pyroclastic glass 74220 is enriched in the lighter isotopes of fe cu and zn and the soils are enriched in the heavier isotopes of fe cu and zn the patterns in the basalts are likely inherited from the source material the light isotope enrichments seen in the orange glass originated during lava fountaining or less probably during partial condensation of vapor and the heavy isotope enrichments in the lunar soils were likely created by a combination of processes that included micrometeorite vaporization and sputtering in the orange glass the light isotope enrichments relative to lunar basalts of zn are larger than those of cu if these enrichments reflect accurately the isotopic composition of the gas they suggest that cu is more volatile than zn in the liquid from which the gas derived a simple model built on the known flux of micrometeorites to the lunar surface and a published estimate that micrometeorites generate 10 times their own mass of vapor predicts heavy isotope enrichments comparable to those observed in soils but only if the regolith gardening rate is set at about one twentieth of the generally accepted value of 1 cm my this discrepancy may reflect the difference in the time constants for micrometeorite milling and decimeter scale gardening or the importance of sputtering

magmatic evolution of lunar highland rocks estimated from trace elements in plagioclase a new bulk silicate moon model with sub chondritic ti ba sr ba and sr al ratios abstract the compositions of host magmas of ferroan anorthosites fan host magmas were estimated from secondary ion mass spectrometry analyses of plagioclase in lunar highland rocks the evolution of the magmas was investigated by considering phase relations based on the melts algorithm and by re examining partition coefficients for trace elements between plagioclase and melts data little affected by post magmatic processes were selected by using plagioclase with relatively primitive sc and co contents the fan host magma contained 90 174 ppm sr 40 119 ppm ba and 0 5 1 3 tio2 and had sub chondritic sr ba and ti ba ratios it is difficult to account for the formation of fan host magma on the basis of magma evolution processes of previously proposed bulk silicate moon models with chondritic ratios for refractory elements at global scale therefore the source of the fan host magma must have had primordial sub chondritic sr ba and ti ba ratios the fan host magmas were consistent in refractory elements with the estimated host mafic magma for feldspathic crust based on lunar meteorites and some very low ti mare rocks from lunar meteorites here we propose an alternative bulk silicate moon model the cbsm model which is enriched in crustal components of proto bodies relative to the present whole earth moon system

exploring the impacts of multiple tidal constituents and varying river flow on long term large scale estuarine morphodynamics by means of a 1 d model tidal asymmetry is an important mechanism generating tidal residual sediment transport trst in tidal environments so far it is known that a number of tidal interactions e g m2 m4 and m2 o1 k1 can induce tidal asymmetry and associated trst however their variability and morphodynamic impacts are insufficiently explored inspired by the river and tidal forcing conditions in the yangtze river estuary we explore the morphodynamic development of a 560 km long estuary under the boundary forcing conditions of varyingly combined tidal constituents and river discharges using a schematized 1 d morphodynamic model for long term millennial simulations we then employ an analytical scheme which integrates sediment transport as a function of flow velocities to decompose the contribution of different tidal interactions on trst and to explain how the river and tidal interactions control trst and associated morphodynamics model results display varying equilibrium bed profiles analytical results suggest that 1 a series of tidal interactions creates multiple tidal asymmetries and associated trst 2 river flow modulates tidal asymmetry nonlinearly in space and 3 more tidal constituents at the sea boundary persistently enhance the seaward trst through river tide interactions it is the combined effects of multiple tidal asymmetries and river tide interactions that determine the net trst and consequent morphodynamic development it thus suggests that tidal harmonics of significant amplitudes need to be considered properly as boundary conditions for long term large scale morphodynamic modeling

water hydrogen in the lunar mantle results from petrology and magma ocean modeling abstract measurements of hydroxyl or water in lunar materials are being used to suggest that melting source regions within the moon contained tens to hundreds of ppm water the compositions of magmatic source regions in the moon can be calculated using magma ocean fractional solidification models given an initial bulk composition our magma ocean models demonstrate that to make a source region with 10 to 200 ppm water the bulk magma ocean must contain 100 to 1000 ppm water or more and in a 1000 km deep lunar magma ocean 1000 ppm water is equivalent to 5 of an earth ocean by weight as solidification of the magma ocean continues water and other incompatible elements are progressively enriched in the evolving liquids the final kreep like liquids would contain the greatest fraction of water we suggest that a bulk magma ocean with over 100 ppm water is prohibited by constraints on these kreep like final magma ocean liquids and by the thermodynamic equilibrium requirement with metallic iron in mare basalts we conclude that bulk lunar interior water contents must be at the low end of the range posited by recent observations

flow asymmetry associated with astronomical tides implications for the residual transport of sediment 1 tidal current asymmetry is usually associated to nonlinear tidal interactions in shallow water generating compound tides and overtides the present paper demonstrates that tidal asymmetry is not only caused by nonlinear tidal interaction but is also generated by astronomical tides in absence of shallow water effects in particular the k1 o1 and m2 constituents give an asymmetrical periodic flow pattern with the largest peak velocities persistently in the same direction a theoretical explanation for this phenomenon is presented and an inventory is made of other subordinate constituents that may contribute to repetitive asymmetric flow patterns tidal current asymmetry may induce residual transport of sediment analytical expressions are derived which quantify the residual transport of sediment due to the k1 o1 and m2 tides as a function of the phases and amplitudes of these constituents and the time lag between variation in suspended sediment transport and flow velocity the residual transport induced by the k1 o1 and m2 tides is compared to the residual transport due to the asymmetry associated with the m2 and m4 tides the former mechanism is particularly relevant in diurnal or mixed mainly diurnal tidal regimes where the k1 and o1 tides are dominant

tectonic evolution of the careon ophiolite northwest spain a remnant of oceanic lithosphere in the variscan belt abstract analysis of the careon unit in the ordenes complex northwest iberian massif has supplied relevant data concerning the existence of a paleozoic oceanic lithosphere probably related to the rheic realm and the early subduction related events that were obscured along much of the variscan belt by subsequent collision tectonics the ophiolite consists of serpentinized harzburgite and dunite in the lower section and a crustal section made up of coarse grained and pegmatitic gabbros an early devonian zircon age documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10

variscan exhumation of a subducted paleozoic continental margin the basal units of the ordenes complex galicia nw spain a structural and metamorphic study was carried out in the basal units of the ordenes complex in spain thought to represent a subducted part of the paleozoic margin of gondwana according to their metamorphic evolution this part of the margin was subducted at the onset of the variscan orogeny becoming part of an accretionary complex developed below a colliding element built previously variations in the pt conditions of the first high pressure metamorphic event along the units indicate a polarity of the subduction to the west subsequent underthrusting of more continental material blocked the subduction and triggered the ascent and exhumation of the basal units whereas the convergence continued recumbent folds and thrusts developed along with successive normal detachments compressional and extensional structures were synchronous or alternated in time and together induced the thinning and tapering of the orogenic wedge and its lateral spreading the unroofing took place locally under an inverted temperature gradient caused by a detachment which carried a part of the hot mantle wedge above the subduction zone over the subducted units

diachronous variscan tectonothermal activity in the nw iberian massif evidence from 40ar 39ar dating of regional fabrics abstract multigrain concentrates of hornblende and muscovite together with whole rock slate phyllite samples have been dated 27 analyses using 40ar 39ar incremental release methods along a systematic traverse across the various lithotectonic structural elements which comprise northwestern sectors of the variscan iberian massif hornblende concentrates from amphibolites in the allochthonous ordenes complex yield plateau isotope correlation ages of 425 ma and 377 ma muscovite concentrates and whole rock slate phyllite from this and the cabo ortegal complex yield plateau ages which range from 367 ma to 295 ma analyses of similar material from the relative autochthon yield plateau ages between 359 ma and 275 ma muscovite concentrates from three late to post kinematic granitic stocks yield plateau ages between 309 ma and 274 ma at least seven of the 40ar 39ar analyses from metamorphic rocks record variable thermal rejuvenation of intracrystalline argon systems associated with emplacement of proximal granitic stocks the remaining analyses may be used to constrain the local age of various variscan tectonothermal events the oldest fabric ages are recorded in allochthonous units whereas the youngest fabric ages occur along the boundary between internal and external zones middle devonian ages are recorded in the allochthon and suggest a chronological continuity with deformational events in the relative autochthon where variscan deformation initiated in the upper devonian and diachronously prograded eastward the first deformational events recorded in the limit within the internal and external zones occured ca 20 25 ma later lower namurian variscan deformation systematically prograded diachronously eastward across the orogen as new crustal material was added along the front of the developing orogenic wedge however the entire orogen remained tectonically active with different structural features forming at different times and at different places an average propagation rate of ca 5 km m y is suggested by consideration of a 20 25 ma difference in correlative fabric ages and present separations

shear stress in subducting continental margin from high pressure moderate temperature metamorphism in the ordenes complex galicia nw spain the ordenes complex galicia nw spain preserves high pressure moderate temperature metamorphism in continental margin rocks subducted during closure of the rheic ocean in the variscan orogeny the exposures extend across c90 km perpendicular to strike and include rocks that reached depths of 30 to 60 km estimates of p t conditions of rocks found near the boundary between overriding and subducting plates range from 430 8c at 1 0 gpa to 520 8c at 1 65 gpa structural reconstructions including these data indicate an angle of subduction between 15 and 308 a mathematical solution and numerical models have been used to estimate shear heating experienced by this well exposed paleo subduction zone best fit of model to thermobarometric results occurs if shear stress in the upper reaches of the fault separating subducting and overriding slabs was c100 mpa constant shear or c10 0 of pressure constant coefficient of friction assuming a convergence rate of 6 cm year 1 at greater depths negative feedback between temperature and shear stress caused the system to approach steady state with decreasing shear stress and with little increase in temperature the decrease in shear stress at temperatures above 400 8c occurs as the rheological properties of the rock at higher temperature and or pressure allow more plastic behavior this suggests that high temperature metamorphism is unlikely to occur in subducting crust without special circumstances a comparison of these results with estimates of shear stress inferred from seismicity and heat flow at active convergent boundaries in the pacific indicates that shear stress is best described as a pressure dependent variable not as a constant shear stress

water in lunar anorthosites and evidence for a wet early moon water has been detected on the lunar surface and attributed to delivery by impacts and the solar wind to a dry early moon spectroscopic detections of water in lunar anorthosites from the apollo collection suggest that a significant amount of water is indigenous to the moon

isotopic fractionation of zinc in tektites abstract tektites are terrestrial natural glasses produced during a hypervelocity impact of an extraterrestrial projectile onto the earth s surface the similarity between the chemical and isotopic compositions of tektites and terrestrial upper continental crust implies that the tektites formed by fusion of such target rock tektites are among the driest rocks on earth although volatilization at high temperature may have caused this extreme dryness the exact mechanism of the water loss and the behavior of other volatile species during tektite formation are still debated volatilization can fractionate isotopes therefore comparing the isotope composition of volatile elements in tektites with that of their source rocks may help to understand the physical conditions during tektite formation for this study we have measured the zn isotopic composition of 20 tektites from four different strewn fields almost all samples are enriched in heavy isotopes of zn compared to the upper continental crust on average the different groups of tektites are isotopically distinct listed from the isotopically lightest to the heaviest muong nong type indochinites 66 64 zn 0 61 0 30 north american bediasites 66 64 zn 1 61 0 49 ivory coast tektites 66 64 zn 1 66 0 18 the australasian tektites others than the muong nong type indochinites 66 64 zn 1 84 0 42 and central european moldavites 66 64 zn 2 04 0 19 these results are contrasted with a narrow range of 66 64 zn 0 0 7 for a diverse spectrum of upper continental crust materials the elemental abundance of zn is negatively correlated with 66 64 zn which may reflect that isotopic fractionation occurred by evaporation during the heating event upon tektite formation simple rayleigh distillation predicts isotopic fractionations much larger than what is actually observed therefore such a model cannot account for the observed zn isotope fractionation in tektites we have developed a more realistic model of evaporation of zn from a molten sphere during its hypervelocity trajectory the molten surface of the tektite will be entrained by viscous coupling with air that will then induce a velocity field inside the molten sphere this velocity field induces significant radial chemical mixing within the tektite that accelerates the evaporation process our model albeit parameter dependent shows that both the isotopic composition and the chemical abundances measured in tektites can be produced by evaporation in a diffusion limited regime

polyphase variscan emplacement of exotic terranes morais and braganca massifs onto iberian successions evidence from 40ar 39ar mineral ages abstract the braganca and morais nappe complexes comprise internally imbricated continental tectonic units including schists deformed metagranite granulite and local eclogite and a structurally underlying ophiolite nappe high pressure assemblages in some of the continental sequences were variably retrogressed during an amphibolite facies metamorphic overprint by contrast rocks within the ophiolite nappe display prograde amphibolite facies assemblages hornblende concentrates from both tectonic units exposed in the braganca nappe complex record 40 ar 39 ar plateau and isotope correlation ages of c 385 390 ma a similar date is recorded by hornblende within mylonitic amphibolite ophiolite protolith along a ductile thrust which separates the two major nappe units muscovite within blastomylonitic metagranite lagoa augen gneiss in upper structural levels of the morais massif records 370 375 ma 40 ar 39 ar plateau ages muscovite within phyllinite developed along a ductile thrust separating the gneiss from the structurally underlying ophiolite nappe records a 375 ma age together the 40 ar 39 ar data suggest that a regionally significant early variscan amphibolite facies metamorphism occurred prior to c 385 390 ma early devonian this was associated with ductile imbrication of continental and ophiolite structural units with resultant formation of a composite nappe complex the composite nappe complex must have been maintained at relatively high structural levels throughout the remaining variscan evolution because there is no evidence for post 370 ma rejuvenation of intracrystalline argon systems in any of crystalline structural units examined this is in marked contrast to a significant late devonian c 330 ma locally high pressure metamorphism which is recorded in structurally underlying elements of the lower allochthon part of a foreland thrust complex composed of metasedimentary units with iberian protolith affinities together available chronologic constraints indicate emplacement of the previously assembled composite nappe complex into its present relative structural position at c 330 ma with resultant deformation and metamorphism of structurally underlying components of the iberian thrust complex

geochemistry of tektites and impact glasses glass produced by melting during impact events is called impact glass or impactite although impact crate ring produces a great variety of shock metamorphosed rocks all of which are called impactites by various authors to a differing extent we restrict the use of this term here to material completely converted into glass the degree of metamorphism seen in different classes of impact materials starting with those showing simple shock effects shock lithification shatter cones diaplectic glasses coesite stishovite lechatelierite impact breccias glass depends on the peak pressure and temperature the rock has experienced as a result of mixing brecciation and similar processes impact glasses also tend to include fragments of less shocked or less homogeneous metamorphosed rocks we limit our discussion here however to the more homogeneous members of the terrestrial impactite family a discussion of lunar impact glasses was given by delano et al 1981 another group of natural glasses are tektites which at first glance are similar to obsidian most tektites are very homogeneous often aerodynam ically shaped spherically symmetric objects that are several centimeters in size and are found in various areas referred to as tektite strewn fields in reflected light they are usually black but in transmitted light they show variations of grey brown and green the surface features gouges furrows grooves pits striations clearly distinguish them from terrestrial volcanic glasses and have probably originated from solution etching and weathering effects on earth baker 1963 lamarche et a1 1984 and from surface stresses occurring during their cooling tektites found in geographically adjacent

a study of non linear tidal propagation in shallow inlet estuarine systems part i observations the offshore tide becomes strongly distorted as it propagates into shallow estuarine systems observations of sea surface elevation and horizontal currents over periods ranging from three days to one year at nine stations within nauset inlet estuary document the non linear interaction of the off shore equilibrium tidal constituents despite strong frictional attenuation within the estuary the overtides and compound tides of m2 s2 and n2 in particular reach significant amplitude resulting in strong tidal distortion high frequency forced constituents in sea surface are phase locked consistently leading the forcing tides by 60 70 resulting in a persistent distortion where falling tide is longer than rising tide forced constituents in currents are more nearly in phase with equilibrium constituents producing flood currents which are shorter but more intense than ebb currents a compound fortnightly tide msf modulates the mean water level such that lowest tides occur during neap phase instead of spring phase this fortnightly tide can be contaminated by storm surge changing the phase characteristics of this constituent implications of the overtides compound tides and lower frequency tides on near bed suspended and dissolved material transport are profound

lunar feldspathic meteorites constraints on the geology of the lunar highlands and the origin of the lunar crust abstract the composition of the lunar crust provides clues about the processes that formed it and hence contains information on the origin and evolution of the moon current understanding of lunar evolution is built on the lunar magma ocean hypothesis that early in its history the moon was wholly or mostly molten this hypothesis is based on analyses of apollo samples of ferroan anorthosites 90 plagioclase molar mg mg fe mg 75 and the assumption that they are globally distributed however new results from lunar meteorites which are random samples of the moon s surface and remote sensing data show that ferroan anorthosites are not globally distributed and that the apollo highland samples used as a basis for the model are influenced by ejecta from the imbrium basin in this study we evaluate anorthosites from all currently available adequately described lunar highland meteorites representing a more widespread sampling of the lunar highlands than apollo samples alone and find that 80 of them are significantly more magnesian than apollo ferroan anorthosites interestingly luna mission anorthosites collected outside the continuous imbrium ejecta are also highly magnesian if the lunar highland crust consists dominantly of magnesian anorthosites as suggested by their abundance in samples sourced outside imbrium ejecta a reevaluation of the lunar magma ocean model is a sensible step forward in the endeavor to understand lunar evolution our results demonstrate that lunar anorthosites are more similar in their chemical trends and mineral abundance to terrestrial massif anorthosites than to anorthosites predicted in a lunar magma ocean this analysis does not invalidate the idea of a lunar magma ocean which seems a necessity under the giant impact hypothesis for the origin of the moon however it does indicate that most rocks now seen at the moon s surface are not primary products of a magma ocean alone but are products of more complex crustal processes

silicon isotopes in lunar rocks implications for the moon s formation and the early history of the earth silicon isotopic data from a range of lunar samples are presented to assess the degree of heterogeneity of the lunar mantle and its similarity to bulk silicate earth bse multi collector inductively coupled plasma mass spectrometry mc icpms was used to analyse 24 samples including both high and low ti basalts as well as highland anorthosites and picritic glasses covering all the apollo sample return missions no systematic 30si differences are found between any of the bulk sample lithologies 2 sd 30silow ti basalt 0 29 0 06 30sihigh ti basalt 0 32 0 09 30silunar glass 0 29 0 05 and 30sihighland rocks 0 27 0 10 the average of the lunar samples is 30si 0 29 0 08 2 sd which is identical to the composition of bse 30si 0 29 0 08 2 sd from savage et al 2010 the bse si isotope composition is thought to be the result of si partitioning between metal and silicate and consequent isotopic fractionation during core formation the moon forming impactor would not be expected to share that composition because it is thought to have been relatively small 0 1 earth masses like mars and formed under relatively low temperatures and pressures that are insufficient for si to partition into the core therefore the identical lunar and bse si isotope data show that si isotopes like those of oxygen must have homogenised in the aftermath of the moon forming impact if smooth particle hydrodynamic simulations of the giant impact are correct in showing that most lunar material should have originated from the impactor rather than the earth the data presented here are in agreement with other isotope systems and experimental studies that indicate that the majority of core formation happened early and before the giant impact it has been predicted pahlevan et al 2011 that the moon and the bse should show a 0 14 offset in 30si for the moon to have an fe fe mg ratio twice that of bse the current resolution and sample population size of the si data for the moon and earth would allow such an offset to be detected the fact that is it not observed can put constraints on the element ratios and lunar budgets as modelled by pahlevan et al 2011 in particular it constrains the fe fe mg ratio of the moon to be only 1 1 3 bse

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

heterogeneous distribution of water in the moon the discovery of water in lunar samples in 2008 challenged the notion that the moon s interior had lost all its volatiles since then analyses of the water concentrations and isotopic compositions in lunar samples taken together suggest that the moon is heterogeneously wet which may lend clues to its origin

hydrogen isotope ratios in lunar rocks indicate delivery of cometary water to the moon water has been found in many lunar rock samples but its sources are unknown isotopic analyses of apollo samples of lunar mare basalts and highlands rocks suggest that a significant volume of water was delivered to the moon by comets shortly after its formation by giant impact

geology and scientific significance of the rumker region in northern oceanus procellarum china s chang e 5 landing region the rumker region 41 45 n 49 69 w is located in northern oceanus procellarum of the moon mons rumker is the most distinctive geological feature in the area the region is characterized by prolonged lunar volcanism late imbrian period to eratosthenian period forming multiple geologic units in the area including very low ti to low ti mare basalts high ti mare basalts and volcanic complexes each geologic unit has distinct element composition and mineral assemblages the rumker region overlying the procellarum kreep terrain was selected as the landing region for china s chang e 5 lunar sample return mission prelanding analyses of the geologic context and scientific potential are reported in this contribution we conducted detailed geological mapping using image spectral and altimetry data fourteen geological units were defined a geologic map was constructed and the geologic history was outlined the western mare units im1 im2 and im3 are imbrian aged 3 4 3 5 ga representing the major stage of lunar mare eruptive volcanism the eastern young mare units em3 and em4 2 ga are among the youngest mare basalts on the moon they have never been explored in situ or studied in the laboratory we suggest that samples returned from the eastern mare unit em4 could answer many fundamental questions and that this unit should be listed as the top priority landing site for chang e 5 sample return mission

geochemical and geochronological cross section of the deep variscan crust the cabo ortegal high pressure nappe northwestern spain the high pressure rocks of the cabo ortegal nappe and related massifs are represented by several tectonometamorphic units which underwent separate histories before regional overthrusting and amphibolite facies recrystallization at 380 ma the occurrence of final cooling is recorded by 40ar 39ar and rb sr mica ages of up to 350 ma u pb zircon dating and sm nd and rb sr isotope data together with ree and major and trace element geochemistry provide constraints on the timing of earlier tectonothermal events and the nature of the protoliths the earliest tectonothermal event occurred at 490 480 ma and corresponds to the emplacement of lree enriched magmas of probable calc alkaline affinity and their metamorphism in the granulite facies this occurred at approximately the same time as the eclogite facies metamorphism of morb like protholiths associated with basic to intermediate granulites together this suggests formation of syn accretion granulites in an active margin setting a second high grade metamorphic event is recorded at 420 ma in metasedimentary formations associated with eclogite like assemblages garnet omphacite plagioclase this event is possibly related to a collisional plate tectonic setting in a back arc basin the age and origin of the associated ultrabasic rocks remains unclear but a late pyroxenite vein has yielded an emplacement age of 390 ma

lunar and terrestrial crust formation planetary crusts may be accreted produced in primordial differentiation or built up piecemeal by serial magmatism the existence of old polygenetic laterally heterogeneous partial melt rocks in the lunar highlands suggests that the moon produced its early crust by serial magmatism this view can be reconciled with lunar eu anomalies previously thought to support the magma ocean model of crust formation if complications in the fractionation of mare basalts are recognized phase equilibrium and magmatic density information for mare basalts suggest a model in which plagioclase fractionation can occur even though plagioclase is not a near liquidus phase the cryptic fractionation of clinopyroxene in morb provides a precedent for this model the necessity for a lunar magma ocean is questioned but a role for a terrestrial magma ocean of sorts at depth is suggested

anticlockwise p t path of granulites from the monte castelo gabbro ordenes complex nw spain the study of mafic and aluminous granulites from the monte castelo gabbro ordenes complex nw spain reveals an anticlockwise p t path that we interpret as related to the tectonothermal activity in a magmatic arc probably an island arc the p t path was obtained after a detailed study of the textural relationships and mineral assemblage succession in the aluminous granulites and comparing these with an appropriate petrogenetic grid additional thermobarometry was also performed the granulites are highly heterogeneous with distinct compositional domains that may alternate even at thin section scale garnets are generally idiomorphic to subidiomorphic and in certain domains of the aluminous granulites they show overgrowths forming xenomorphic coronas around a more or less idiomorphic core both types of garnets show significant ca enrichment at the crystal rims which together with the other mineralogical and textural characteristics is compatible with a pressure increase with low t variation p t estimations indicate a peak of t 800 c and p 9 5 kbar attained after a significant increase in pressure that took place at high temperatures in the sillimanite field we suggest that this kind of trajectory probably anticlockwise is compatible only with a terrane heated by an intense magmatic activity after or during tectonic crustal thickening magmatic injection at the base and or into the crust which is characteristic of magmatic arcs