visualisation and quantification of cv chondrite petrography using micro tomography abstract micro computed tomography is a non destructive technique that allows the study of 3d meteorite petrography the technique produces a unique and instructive visualisation of the meteorite for quantifying its components we studied the overall petrography of the two cv chondrites allende and mokoia to constrain their formation histories a set of movies and stereographic images detail the 3d petrography component modal abundances agree with previous reports and modal abundance differences between allende and mokoia support the chondrule matrix complementarity and that chondrules and matrix formed from the same chemical reservoir we identified two types of chondrules a normal type and one where a normal type i or ii chondrule is almost completely encapsulated by an opaque rich layer this layer was probably acquired during a late stage condensation process the appearance of opaques in chondrules and matrix is different not supporting a genetic relationships between these low abundances of compound chondrules 1 75 vol in allende and 2 50 vol in mokoia indicate low chondrule densities and or low relative component velocities in chondrule formation regions porosities on a scale

zinc isotope composition of the earth and its behaviour during planetary accretion abstract the terrestrial planets are depleted in volatile elements with respect to chondritic meteorites their possible building blocks however the timing extent and origin of volatile depletion is debated zinc is a moderately volatile element mve whose stable isotopic composition can distinguish when and where this depletion took place here we report data for 40 ultramafic rocks comprising pristine upper mantle peridotites from the balmuccia orogenic lherzolite massif and archean komatiites that together define the zn isotope composition of the earth s primitive mantle peridotites and komatiites are shown to have indistinguishable zn isotopic compositions of 66zn 0 16 0 06 2sd with 66zn the per mille deviation of 66zn 64zn from the jmc lyon standard implying a constant zn isotope composition for the silicate earth since 3 5 ga after accounting for zn sequestration during core formation the earth falls on the volatile depleted end of a carbonaceous chondrite array in 66zn zn mg space implying earth avoided modification of its mve budgets during late accretion e g during a giant impact in contrast to the moon the moon deviates from the chondritic array in a manner consistent with evaporative loss of zn where its 66zn co varies with mn na implying post nebular volatile loss is more pronounced on smaller bodies should the giant impact deliver the earth s volatile complement of pb and ag it cannot account for the budget of lithophile mves e g zn rb mn whose abundances reflect those of earth s nebular building blocks the earth initially accreted from material that experienced chemical and mass dependent isotopic fractionation akin to carbonaceous chondrites though volatile depletion was more pronounced on earth

comparative stable isotope geochemistry of ni cu zn and fe in chondrites and iron meteorites high precision ni isotopic variations are reported for the metal phase of equilibrated and unequilibrated ordinary chondrites carbonaceous chondrites iron meteorites mesosiderites and pallasites we also report new zn and cu isotopic data for some of these samples and combine them with literature fe cu and zn isotope data to constrain the fractionation history of metals during nebular vapor solid and planetary metal sulfide silicate phase changes the observed variations of the 62ni 58ni 61ni 58ni and 60ni 58ni ratios vary linearly with mass difference and define isotope fractionation lines in common with terrestrial samples this implies that ni was derived from a single homogeneous reservoir while no 60ni anomaly is detected within the analytical uncertainties ni isotopic fractionation up to 0 45 per mass difference unit is observed the isotope compositions of ni and zn in chondrites are positively correlated we suggest that in ordinary chondrites exchange between solid phases in particular metal and silicates and vapor followed by mineral sorting during accretion are the main processes controlling these isotopic variations the positive correlation between ni and zn isotope compositions contrasts with a negative correlation between ni and zn and cu isotope compositions which when taken together do not favor a simple kinetic interpretation the observed transition element similarities between different groups of chondrites and iron meteorites are consistent with the genetic relationships inferred from oxygen isotopes iiia pallasites and iva l chondrites copper is an exception which we suggest may be related to separate processing of sulfides either in the vapor or during core formation

oxygen isotope studies of carbonaceous chondrites abstract the carbonaceous chondrites display the widest range of oxygen isotopic composition of any meteorite group as a consequence of the interaction of primordial isotopic reservoirs in the solar nebula these isotopic variations can be used to identify the reservoirs and to determine conditions and loci of their interactions we present a comprehensive set of whole rock analyses of cv co ck cm cr ch and ci chondrites as well as selected components of some of these meteorites a simple model is developed which describes the isotopic behavior during parent body aqueous alteration processes the process of thermal dehydration also produces a recognizable effect in the oxygen isotopic composition

the ayers rock australia earthquake of 28 may 1989 a temporally isolated mb 5 8 intraplate event abstract at 0255 utc on 28 may 1989 an m b 5 8 earthquake shook the yulara resort and uluru national park in the northern territory of australia the epicenter lay 40 km west of ayers rock in an area where moderate size earthquakes had not previously been recorded within 215 km although many people at yulara and uluru were alarmed damage to buildings was minimal the australian national university anu installed an array of 11 seismographs in the epicentral area 6 days after the m b 5 8 event no aftershocks were detected by the anu network during 2 weeks of recording with an estimated detection threshold of magnitude 1 to 0 another group of seismologists who operated a single recorder near uluru beginning 59 hours after the main shock and continuing through july and 6 other recorders for 6 days in early june also failed to observe any aftershocks within the sensitivity of the arrays the ayers rock event was a temporally isolated earthquake the absence of aftershock activity is in sharp contrast to the seismicity pattern following two magnitude 5 2 earthquakes near tennant creek in january 1987 and to other earthquakes of magnitude 4 2 to 6 3 observed in continental intraplate settings worldwide

formation timescales of cv chondrites from component specific hf w systematics abstract carbonaceous chondrites are an important meteorite group that closely resembles the bulk composition of the solar system we report the first elemental and isotope dataset for hf w in carbonaceous chondrites that includes chondrules matrix magnetic fractions as well as bulk compositions our study focuses on the three cv3 chondrites allende vigarano and bali compared to bulk chondrites matrix splits have low hf w ratios and e 182 w compositions whereas chondrule splits are characterized by high but more variable hf w ratios and e 182 w compositions thus hf w ratios behave complementary between chondrules and matrix in the analysed cv chondrites supporting the view that both components formed from the same parental reservoir strong nucleosynthetic effects were observed in most of the analysed cv3 components especially in matrices and chondrule splits that were found to have large e 183 w anomalies of several e units all separates define a rough correlation between initial 182 w 184 w and 183 w 184 w ratios in agreement with theoretical model trends based on calculations for stellar nucleosynthesis our results therefore indicate a heterogeneous distribution of s and r process w isotopes among the different cv3 chondrite components arguing for selective thermal processing of early solar system matter during chondrule formation after correcting for nucleosynthetic anomalies chondrules and matrix splits of reduced vigarano as well as oxidised allende cv3 chondrites define a linear correlation in e 182 w vs 180 hf 184 w space which is interpreted as an isochron covering an age interval within the first 2 6 ma after solar system formation as peak metamorphic temperatures for cv3 chondrites were well below the 182 hf 182 w closure temperature the resulting isochron within its error most likely defines a common formation interval for all components the calculated age interval is for the first time based on a combined chondrule matrix isochron a marked difference compared to previous studies where only chondrules were analysed notably our formation age interval covers previously reported chondrule formation ages determined using 26 al and pb pb chronometry illustrating that chondrule and matrix formation started contemporaneously with cai formation and lasted over a time interval of about 2 3 ma our results also corroborate previous models from ordinary chondrites in that chondrite parent bodies were not the first planetesimals to have formed in the early solar system

global charts of ocean tide loading effects global ocean tide loading charts of the radial displacement the potential divided by g gravity acceleration and the gravity effect have been computed using the 11 constituents m2 s2 n2 k2 k1 o1 p1 q1 mf mm ssa of schwiderski s tidal model these new charts have a resolution of 1 1 on the continents as well as on the oceanic area a description of farrell s convolution method to compute the loading effects is given and an estimate of the numerical errors leads to the conclusion that these global charts have a precision better than 2 5 independent of the accuracy of schwiderski s maps the current approximation of the loading effects by a proportionality relation with the local oceanic tides is also compared with farrell s convolution method departures of several centimeters systematically appear in particular over the continental shelves we then show that the maps of the oceanic tides deduced from satellite altimetry could be corrected for the loading effect by an iterative computational procedure based on our algorithm of farrell s convolution

rubidium isotopic composition of the earth meteorites and the moon evidence for the origin of volatile loss during planetary accretion abstract understanding the origin of volatile element variations in the inner solar system has long been a goal of cosmochemistry but many early studies searching for the fingerprint of volatile loss using stable isotope systems failed to find any resolvable variations an improved method for the chemical purification of rb for high precision isotope ratio measurements by multi collector inductively coupled plasma mass spectrometry this method has been used to measure the rb isotopic composition for a suite of planetary materials including carbonaceous ordinary and enstatite chondrites as well as achondrites eucrite angrite terrestrial igneous rocks basalt andesite granite and apollo lunar samples mare basalts alkali suite volatile depleted bodies e g hed parent body thermally metamorphosed meteorites are enriched in the heavy isotope of rb by up to several per mil compared to chondrites suggesting volatile loss by evaporation at the surface of planetesimals in addition the moon is isotopically distinct from the moon in rb the variations in rb isotope compositions in the volatile poor samples are attributed to volatile loss from planetesimals during accretion this suggests that either the rb and other volatile elements were lost during or following the giant impact or by evaporation earlier during the accretion history of theia

the formation and alteration of the renazzo like carbonaceous chondrites i implications of bulk oxygen isotopic composition abstract to better understand the role of aqueous alteration on the cr chondrite parent asteroid a whole rock oxygen isotopic study of 20 meteorites classified as renazzo like carbonaceous chondrites cr was conducted the cr chondrites analyzed for their oxygen isotopes were dhofar 1432 elephant moraine eet 87770 eet 92042 eet 96259 gao guenie b graves nunataks gra 95229 gra 06100 grosvenor mountains gro 95577 gro 03116 lapaz ice field lap 02342 lap 04720 meteorite hills met 00426 north west africa nwa 801 pecora escarpment pca 91082 queen alexandra range que 94603 que 99177 and yamato 793495 y 793495 three of the meteorites asuka 881595 a 881595 gra 98025 and met 01017 were found not to be cr chondrites the remaining samples concur petrographically and with the well established oxygen isotope mixing line for the cr chondrites their position along this mixing line is controlled both by the primary oxygen isotopic composition of their individual components and their relative degree of aqueous alteration combined with literature data and that of this study we recommend the slope for the cr mixing line to be 0 70 0 04 2 with a 17 o intercept of 2 23 0 14 2 thin sections of al rais shisr 033 renazzo and all but 3 samples analyzed for oxygen isotopes were studied petrographically the abundance of individual components is heterogeneous among the cr chondrites but feo poor chondrules and matrix are the most abundant constituents and therefore dominate the whole rock isotopic composition the potential accreted ice abundance physico chemical conditions of aqueous alteration e g temperature and composition of the fluid and its duration control the degree of alteration of individual cr chondrites combined with literature data we suggest that lap 02342 was exposed to lower temperature fluid during alteration than gra 95229 with only two falls terrestrial alteration of the cr chondrites complicates the interpretation of their whole rock isotopic composition particularly in the most aqueously altered samples and those with relatively higher matrix abundances we report that que 99177 is the isotopically lightest whole rock cr chondrite known 18 o 2 29 17 o 4 08 possibly due to isotopically light unaltered matrix which shows that the anhydrous component of the cr chondrites is isotopically lighter than previously thought although it experienced aqueous alteration que 99177 provides the best approximation of the pristine cr chondrite parent body s oxygen isotopic composition before aqueous alteration took place using this value as a new upper limit on the anhydrous component of the cr chondrites water rock ratios were recalculated and found to be higher than previously thought ratios now range from 0 281 to 1 157 we also find that according to their oxygen isotopes a large number of cr chondrites appear to be minimally aqueously altered although sample heterogeneity complicates this interpretation

rupture process of a multiple main shock sequence analysis of teleseismic local and field observations of the tennant creek australia earthquakes of january 22 1988 on january 22 1988 three large intraplate earthquakes with ms 6 3 6 4 and 6 7 occurred within a 12 hour period near tennant creek australia these earthquakes which occurred over a small interval of time and within a small volume of space present a unique opportunity to study the rupture process of the class of intraplate earthquakes that occur as multiple main shocks broadband displacement and velocity records of body waves from teleseismically recorded data are analyzed to determine source mechanisms depths and complexity of rupture of each of the three main shocks hypocenters of an additional 150 foreshocks and aftershocks constrained by local arrival time data and field observations of surface rupture are used to complement the source characteristics of the main shocks in order to derive as complete a description of the rupture process as possible the interpretation of the combined data sets suggests that the overall rupture process involved unusually complicated stress release as locations of the main shock hypocenters progressively moved from west to east we infer that the first and third main shocks denoted as ms1 and ms3 produced the southeast northwest trending scarps observed at the western end the kunayungku fault and at the eastern end the east end of the lake surprise fault respectively of the rupture zone the epicenter of the only immediate foreshock was located in the gap between these two fault scarps ms1 nucleated near this epicenter and ruptured upward and to the northwest from a depth of 6 5 km ms3 ruptured predominantly to the se at a depth of 4 5 km the second main shock ms2 is inferred to have produced the deformation of the southwest trending central scarp segment the western end of the lake surprise fault from the sense of thrusting seen at the surface and from the distribution of aftershock hypocenters the south dipping nodal planes derived from waveform modeling are identified as the fault planes for earthquakes ms1 and ms3 in contrast the dip of the central fault scarp is reversed relative to the dips of the western and eastern fault scarps the rupture process of ms2 turns out to be commensurately complex and sufficiently explains the geological complexity ms2 consisted of three subevents the southeast dipping nodal plane of the first two subevents is coplanar with a southeast dipping plane implied by locations of aftershocks which did not break the surface choice of the north dipping plane as the rupture plane of the third subevent consistent with the surface deformation and coplanar with a second plane delineated by aftershocks would imply conjugate faulting the majority of the aftershocks are concentrated near the edges of the fault planes and there is an absence of activity in the center of the planes the areas of absent activity may represent the failed asperities of the main shocks in which substantial stress relief occurred the rupture process of each main shock is characterized by the rapid release of energy followed by a much slower release of moment and by aftershock zones whose dimensions exceed the inferred dimensions of the rupture these characteristics suggest that substantial slow slip occurred on each of the three fault interfaces that was not accompanied by major energy release the first main shock nucleated at the deepest part of its aftershock zone and ruptured upward in contrast ms2 and ms3 nucleated at depths that were one third to one half of the maximum depth of their aftershock zones this variation of focal depth and the strong increase of moment and radiated energy with each main shock imply that lateral variations of strength were more important than vertical gradients of shear stress in controlling the progression of rupture

ag isotopic and chalcophile element evolution of the terrestrial and martian mantles during accretion new constraints from bi and ag metal silicate partitioning abstract the earth s timing of accretion and acquisition of moderately volatile compounds is uncertain hafnium w and mn cr isotopic data can bracket the timing of early planetary differentiation and core formation the ag pd system has also been utilized but its application has been limited by a lack of high pressure and temperature metal silicate partitioning for pd and ag because ag and bi are volatile chalcophile siderophile elements understanding their early distribution can constrain the origin of volatile elements in differentiated bodies and planets unfortunately neither ag or bi have been studied across the wide range of pressure and temperature conditions that are relevant to accretion and core mantle differentiation here new high pressure and temperature multi anvil metal silicate equilibrium experiments for bi and ag have been carried out at conditions relevant to planetary accretion and metal silicate differentiation that allow a more refined and complete understanding of element partitioning during core formation the new metal silicate partitioning data are combined with previously reported data and utilized to predict the distributions of bi pd and ag at conditions of accretion relevant for earth and mars application of the new partitioning results to earth shows that d bi and d ag d metal silicate concentration ratio are lowered due to the effect of pressure and si alloyed in the metallic liquid resulting in higher predicted mantle bi and ag abundances than in the bulk silicate earth bse as well as high and variable pd ag the unradiogenic ag isotopic composition of the bse could have been generated by early accretion of volatile poor high pd ag pre cursors followed by later accretion of volatile rich low pd ag material in agreement with earlier studies of pd ag and mn cr schonbachler et al 2010 however these main accretion phases would have to be followed by segregation of a sulfide liquid at least 1 5 of magma ocean at high pressures 30 gpa to explain the primitive upper mantle pum bi pd and ag as well as au pt cu and ni concentrations as proposed previously if the early accreted bulk earth was volatile depleted with high pd ag ratios portions of the mantle may contain ancient domains that developed positive 107ag isotopic anomalies as also argued by noble gases nd w and os isotopes in comparison bi pd and ag concentrations in the martian mantle could have been set by simple metal silicate equilibrium mars accreted and differentiated relatively rapidly while also developing a deep magma ocean with a high pd ag ratio that could have evolved positive 107ag anomalies in contrast to earth measurements on shergottites may reveal these predicted ag isotopic anomalies

the formation of chondrules petrologic tests of the shock wave model chondrules are millimeter sized rounded igneous rocks within chondritic meteorites their textures and fractionated mineral chemistries suggest that they formed by repeated localized brief minutes to hours melting of cold aggregates of mineral dust in the protoplanetary nebula astrophysical models of chondrule formation have been unable to explain the petrologically diverse nature of chondrites however a nebular shock wave model for chondrule formation agrees with many of the observed petrologic and geochemical properties of chondrules and shows how particles within the nebula are sorted by size and how rims around chondrules are formed it also explains the volatile rich nature of chondrule rims and the chondrite matrix

contributors to chromium isotope variation of meteorites we report the results of a comprehensive high precision survey of the cr isotopic compositions of primitive chondrites along with some differentiated meteorites to ensure complete dissolution of our samples they were first fused with lithium borate tetraborate at 1050 1000 c relative to the nist cr standard srm 3112a carbonaceous chondrites exhibit excesses in 54cr 52cr from 0 4 to 1 6e 1e 1 part in 10 000 and ordinary chondrites display a common 54cr 52cr deficit of 0 4e analyses of acid digestion residues of chondrites show that carbonaceous and ordinary chondrites share a common 54cr enriched carrier which is characterized by a large excess in 54cr 52cr up to 200e associated with a very small deficit in 53cr 52cr 2e we did not find 54cr anomalies in either bulk enstatite chondrites or in leachates of their acid digestion residues this either requires that the enstatite chondrite parent bodies did not incorporate the 54cr anomaly carrier phase during their accretion or the phase was destroyed by parent body metamorphism chromium in the terrestrial rocks and lunar samples analyzed here show no deviation from the nist srm 3112a cr standard the eucrite and martian meteorites studied exhibit small deficits in 54cr 52cr the 54cr 52cr variations among different meteorite classes suggest that there was a spatial and or temporal heterogeneity in the distribution of a 54cr rich component in the inner solar system we confirm the correlated excesses in 54cr 52cr and 53cr 52cr for bulk carbonaceous chondrites but the new data yield a steeper slope 6 6 than that reported in shukolyukov and lugmair 2006 the correlated excesses may affect the use of the mn cr chronometer in carbonaceous chondrites we could not confirm the bulk carbonaceous chondrite mn cr isochron reported by shukolyukov and lugmair 2006 and moynier et al 2007 mostly because we find much smaller total variations in e53cr 0 2 all bulk chondrites have small e53cr excesses up to 0 3 relative to the earth most likely reflecting the sub chondritic mn cr ratio of the earth the e53cr variations in chondrites do seem to grossly correlate with mn cr and yield an initial solar system 53mn 55mn value of 5 4 2 4 10 6 corresponding to an absolute age of 4566 4 2 2 ma nuclear interactions with cosmic rays result in coupled excesses in e54cr and e53cr with a 4 1 ratio in phases with high fe cr these are most dramatically demonstrated in the iron meteorite carbo showing excesses in e54cr of up to 140e these new results show that the mn cr chronometer should be used with caution in samples minerals with high fe cr and long cosmic ray exposure ages

re examining the role of chondrules in producing the elemental fractionations in chondrites the matrices of all primitive chondrites contain presolar materials circumstellar grains and interstellar organics in roughly ci abundances suggesting that all chondrites accreted matrix that is dominated by a ci like component the matrix normalized abundances of the more volatile elements condensation temperatures 750800 k in carbonaceous and ordinary chondrites are also at or slightly above ci levels the modest excesses may be due to low levels of these elements in chondrules and associated metal subtraction of a ci like matrix component from a bulk ordinary chondrite composition closely matches the average composition of chondrules determined by instrumental neutron activation analysis inaa if some fe metal is added to the chondrule composition measured matrix compositions are not ci like sampling bias and secondary redistribution of elements may have played a role but the best explanation is that 1030 of refractory rich volatile depleted material was added to matrix if most of the more volatile elements are in a ci dominated matrix the major and volatile element fractionations must be largely carried by chondrules there is both direct and indirect evidence for evaporation during chondrule formation type iia and type b chondrules could have formed from a mixture of ci material and material evaporated from type ia chondrules the mg si fe fractionations in the ordinary chondrites can be reproduced with the loss of type ia chondrule material and associated metal the loss of evaporated material from the chondrules could explain the volatile element fractionations mechanisms for how these fractionations occurred are necessarily speculative but two possibilities are briefly explored

origin and chronology of chondritic components a review abstract mineralogical observations chemical and oxygen isotope compositions absolute 207pb 206pb ages and short lived isotope systematics 7be 7li 10be 10b 26al 26mg 36cl 36s 41ca 41k 53mn 53cr 60fe 60ni 182hf 182w of refractory inclusions ca al rich inclusions cais and amoeboid olivine aggregates aoas chondrules and matrices from primitive unmetamorphosed chondrites are reviewed in an attempt to test i the x wind model vs the shock wave model of the origin of chondritic components and ii irradiation vs stellar origin of short lived radionuclides the data reviewed are consistent with an external stellar origin for most short lived radionuclides 7be 10be and 36cl are important exceptions and a shock wave model for chondrule formation and provide a sound basis for early solar system chronology they are inconsistent with the x wind model for the origin of chondritic components and a local irradiation origin of 26al 41ca and 53mn 10be is heterogeneously distributed among cais indicating its formation by local irradiation and precluding its use for the early solar system chronology 41ca 41k and 60fe 60ni systematics are important for understanding the astrophysical setting of solar system formation and origin of short lived radionuclides but so far have limited implications for the chronology of chondritic components the chronological significance of oxygen isotope compositions of chondritic components is limited the following general picture of formation of chondritic components is inferred cais and aoas were the first solids formed in the solar nebula 4567 4568 myr ago possibly within a period of 10 and have 26al 27al 0 similar to those in chondrules 5 nebular gas the majority of chondrules within a chondrite group may have formed over a much shorter period of time

complementary element relationships between chondrules and matrix in rumuruti chondrites abstract the complimentary chemical composition of chondrules and matrix has so far only been studied in carbonaceous chondrites we have extended these studies to the matrix rich rumurutis we have determined the chemical composition of 27 bulk chondrules and 100 matrix spots in unequilibrated fragments of three different rumuruti r chondrites nwa 2446 nwa 753 hughes 030 also the bulk chemical composition of nwa 753 was determined bulk r chondrites have about ci chondritic solar ratios of fe mg 1 89 al ti 18 62 and al ca 0 94 while chondrules and matrix are complementary to each other mean fe mg ratios in chondrules are 0 43 nwa 2446 0 36 nwa 753 and 0 34 hughes chondrules are depleted in fe while matrices are enriched in fe with respective values of 2 59 2 45 and 2 39 bulk fe mg ratio of nwa 753 the only sample which is unaffected by terrestrial weathering is reproduced by careful mass balance calculations using compositions and abundances of chondrules matrix and sulphides from the same thin section refractory element ratios are also complementary al ti and al ca are sub chondritic in chondrules al ti 10 43 in nwa 753 12 24 in nwa 2446 and 11 47 in hughes 030 al ca 0 66 in nwa 2446 0 53 in nwa 753 and 0 46 in hughes 030 while matrices generally have super chondritic al ca and al ti ratios al ti 28 00 in nwa 2446 23 20 in nwa 753 and 19 00 in hughes 030 al ca 2 30 in nwa 2446 1 90 in nwa 753 and 0 41 in hughes 030 calcium is enriched in the hughes 030 matrix due to terrestrial weathering these complementary element ratios and the ci chondritic bulk strongly suggest a common reservoir from which all r chondrite components formed similar to carbonaceous chondrites further super chondritic si mg and ci chondritic fe mg ratios in bulk r chondrites require addition of si to their reservoir most probably before chondrule formation

the origin of volatile element depletion in early solar system material clues from zn isotopes in chondrules abstract volatile lithophile elements are depleted in the different planetary materials to various degrees but the origin of these depletions is still debated stable isotopes of moderately volatile elements such as zn can be used to understand the origin of volatile element depletions samples with significant volatile element depletions including the moon and terrestrial tektites display heavy zn isotope compositions i e enrichment of 66zn vs 64zn consistent with kinetic zn isotope fractionation during evaporation however luck et al 2005 found a negative correlation between 66 zn and 1 zn between ci cm co and cv chondrites opposite to what would be expected if evaporation caused the zn abundance variations among chondrite groups we have analyzed the zn isotope composition of multiple samples of the major carbonaceous chondrite classes ci 1 cm 4 cv 2 co 4 cb 2 ch 2 ck 4 and ck cr 1 the bulk chondrites define a negative correlation in a plot of 66 zn vs 1 zn confirming earlier results that zn abundance variations among carbonaceous chondrites cannot be explained by evaporation exceptions are cb and ch chondrites which display zn systematics consistent with a collisional formation mechanism that created enrichment in heavy zn isotopes relative to the trend defined by ci ck we further report zn isotope analyses of chondrite components including chondrules from allende cv3 and mokoia cv3 as well as an aliquot of allende matrix all chondrules are enriched in light zn isotopes 500 ppm on 66zn 64zn relative to the bulk contrary to what would be expected if zn were depleted during evaporation on the other hand the matrix has a complementary heavy isotope composition we report sequential leaching experiments in un equilibrated ordinary chondrites which show sulfides are isotopically heavy compared to silicates and the bulk meteorite by ca 0 65 per mil on 66zn 64zn we suggest isotopically heavy sulfides were removed from either chondrules or their precursors thereby producing the light zn isotope enrichments in chondrules

chondrules matrix and coarse grained chondrule rims in the allende meteorite origin interrelationships and possible precursor components bulk compositions of 20 chondrules 13 coarse grained chondrule rims and two composite samples of matrix material from cv3 allende were determined by instrumental neutron activation analysis three rare nonporphyritic cv chondrules from allende leoville and vigarano were analyzed by broad beam electron microprobe analysis chondrule precursor components deduced from chondrule compositions are characterized by 1 refractory and semi refractory lithophiles with low feo 2 common siderophiles and chalcophiles 3 common to slightly volatile lithophiles si cr mn and modal pyroxene with moderately high feo feo mgo 4 moderately volatile siderophiles and 5 alkalies these precursor components can be explained by plausible processes occurring in the solar nebula the precursor components of coarsegrained rims are apparently the same as those of chondrules these components differ from those inferred previously for oc eh or cm co chondrules in general the compositions of coarse grained rims are more similar to the mean chondrule composition than to those of the chondrules they enclose rim siderophile contents are generally 2 5x greater than those in the chondrules and 0 5 to 2x those in bulk allende rims as a group are more homogeneous than chondrules suggesting that rims formed from finer grained precursors several chondrules and rims have fractionated rare earth patterns and may have been affected by metamorphism the enclosure of some coarse grained rims by fine grained matrix like rims that are almost certainly of nebular origin indicates that coarse grained rims were also formed in the nebula two matrix samples are similar in composition to some coarse grained rims suggesting that matrix was derived from similar compositional reservoirs of nebular dust chondrules with coarse grained rims were reheated in space following the accretion of dusty coatings this restricts plausible chondrule forming mechanisms to those that allow multiple nebular heating events

coupled 63cu and 16o excesses in chondrites abstract recent developments in multiple collector magnetic sector icp ms inductively coupled plasma mass spectrometry have permitted the relative abundances of the two isotopes 63 and 65 of copper to be measured with unprecedented precision 40 ppm here we report cu isotopic variations among eight carbonaceous chondrites ccs from the ci cm co and cv groups and the presently ungrouped tagish lake and 10 ordinary chondrites ocs from the h l and ll groups the widest isotopic range of 0 8 per a m u is observed for the carbonaceous chondrites copper in carbonaceous chondrites becomes isotopically lighter with petrologic type in the order 1 to 3 but seems extremely homogeneous for each type the cu isotopic composition of tagish lake confirms its other characteristics that are intermediate between ci and cm in three of the groups ci cm co as well as for tagish lake 63 cu excess over terrestrial mantle abundances correlates well with 16 o excess for all four groups 63 cu excess also correlates remarkably well with elemental refractory volatile ratios e g ca mn for ordinary chondrites small differences exist between the h l and ll groups with cu becoming isotopically heavier in that order equilibrated and unequilibrated samples however exhibit the same cu isotopic signature within each group although the range of cu isotopic compositions in ordinary chondrites is smaller than in carbonaceous chondrites 63 cu excesses still correlate with 16 o excesses the observed trends of isotopic variation seem incompatible with a single stage fractionation process by either volatilization or low temperature metamorphism the correlations between 63 cu excesses and 16 o excesses suggest the presence of at least two and perhaps three isotopically distinct cu reservoirs in the early solar system 1 an earth like reservoir common to the ci and ll probably representing the main cu stock of the inner solar system 2 a reservoir present in all carbonaceous chondrites but most abundant in cv with large 63 cu and 16 o excesses this reservoir is probably hosted in refractory material and 3 possibly a third reservoir present in ordinary chondrites the oc trend may also be explained as a mixture of the first two cu reservoirs if its oxygen was first equilibrated with nebular gas the coexistence of 63 cu and 16 o excesses in the same component raises the issue of how volatile cu was preserved in refractory material a strong correlation between 63 cu 65 cu and ni cu ratios suggests that 63 cu excess may have originated as more refractory 63 ni t 1 2 100 yr upon irradiation of refractory grains by electromagnetic flares and particle bursts during the t tauri phase of the sun

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

zinc isotopes in heds clues to the formation of 4 vesta and the unique composition of pecora escarpment 82502 the 66zn permil deviation of the 66zn 64zn ratio from a terrestrial standard values for a suite of 20 non antarctic hed howardite eucrite diogenite meteorites and one mesosiderite and for 8 antarctic eucrites and diogenites were measured in order to determine the role of volatization in the formation of their presumed parent body the asteroid 4 vesta the 20 non antarctic heds had 66zn values that ranged from 2 0 to 1 67 with a mean value of 0 01 0 39 2se this range likely represents a small scale heterogeneity due to brecciation induced by multiple impacts the non antarctic eucrites 66zn 0 00 0 58 2se n 12 were isotopically the same as the diogenites 66zn 0 31 0 80 2se n 4 and the howardites 66zn 0 26 0 37 2se n 4 on average non antarctic eucrite falls were isotopically heavier 0 50 than non antarctic finds 1 00 the antarctic finds studied were all unbrecciated samples and they were significantly heavier than the non antarctic samples with a 66zn range of 1 63 to 6 22 for 4 eucrites mean 4 32 and 0 94 to 1 60 for 3 diogenites mean 1 23 excluding one anomalous sample while their zn concentration is significantly lower than the brecciated samples these data suggest that the unbrecciated eucrites probably represent the eucritic crust shortly after differentiation and cooling of the parent asteroid at which time volatization of lighter zinc isotopes led to an isotopically heavy crust early impact events caused the ejection of these unbrecciated meteorites which were subsequently spared from brecciation caused by multiple additional impacts on the much larger vesta the range of 66zn values and zn concentration for the brecciated heds in this study supports a major contribution to the vestan surface by chondritic impactors 1 30 66zn 0 76 for ordinary and carbonaceous chondrites the anomalous eucrite pca 82502 66zn 7 75 is significantly isotopically lighter than the other heds and is the natural sample with the lightest zn isotopic composition reported in the solar system to date this meteorite most likely originated from a distinct parent body

intensity relations for australian earthquakes although intensity data are essentially derived from qualitative observations they can be used to estimate basic earthquake parameters such as hypocentres and magnitudes particularly when instrumental observations are not available in this study the intensity information was used from 138 earthquakes to derive relations which enable earthquake magnitudes to be determined from intensity data the earthquakes ranged in size from ml 1 3 to ml 7 2 and the felt areas ranged from 8 km2 to 2 5 106 km2 we obtained the following results 1 ml 0 35 0 12 log rp 2 0 63 0 41 log rp 1 87 0 36 2 ml 0 38 0 19 log riv 2 0 49 0 66 log riv 2 38 0 57 3 ml 1 35 0 34 0 57 0 06 io 4 ml 0 024 0 014 k2 0 061 0 029 k 1 51 1 46 where io is the maximum observed modified mercalli mm intensity k the sponheuer earthquake parameter rp the equivalent radius of the mmiii isoseismal riv the equivalent radius of the mmiv isoseismal and ml the richter magnitude quadratic terms are necessary in relations 1 2 and 4 because of the breakdown of the simple kanai relation at distances close 10 km to the epicentre rather surprisingly it was found that for earthquakes smaller than ml 6 eqns 1 and 3 are more consistent with richter s results for california than with those obtained by nuttli et al for the eastern united states there is excellent agreement between our results and those obtained by sibol et al for central and eastern north america for estimating ml eqn 1 is preferred because the observations have a lower rms deviation about the line of least squares fit

testing the chondrule rich accretion model for planetary embryos using calcium isotopes abstract understanding the composition of raw materials that formed the earth is a crucial step towards understanding the formation of terrestrial planets and their bulk composition calcium is the fifth most abundant element in terrestrial planets and therefore is a key element with which to trace planetary composition however in order to use ca isotopes as a tracer of earth s accretion history it is first necessary to understand the isotopic behavior of ca during the earliest stages of planetary formation chondrites are some of the oldest materials of the solar system and the study of their isotopic composition enables understanding of how and in what conditions the solar system formed here we present ca isotope data for a suite of bulk chondrites as well as allende cv chondrules we show that most groups of carbonaceous chondrites cv ci cr and cm are significantly enriched in the lighter ca isotopes 44 40 ca 0 1 to 0 93 compared with bulk silicate earth 44 40 ca 1 05 0 04 huang et al 2010 or mars while enstatite chondrites are indistinguishable from earth in ca isotope composition 44 40 ca 0 91 to 1 06 chondrules from allende are enriched in the heavier isotopes of ca compared to the bulk and the matrix of the meteorite 44 40 ca 1 00 to 1 21 this implies that earth and mars have ca isotope compositions that are distinct from most carbonaceous chondrites but that may be like chondrules this ca isotopic similarity between earth mars and chondrules is permissive of recent dynamical models of planetary formation that propose a chondrule rich accretion model for planetary embryos

a new metal rich chondrite grouplet abstract a new grouplet of primitive metal rich chondrites here called the cb c carbonaceous b bencubbinite chondrites has been recognized it includes bencubbin weatherford hammadah a1 hamra hh 237 and queen alexandra range que 94411 paired with que 94627 their mineral compositions as well as their oxygen and nitrogen isotopic compositions indicate that they are closely related to the cr and ch chondrites all of which are members of the more inclusive cr clan cb chondrites have much greater metal silicate ratios than any other chondrite group widely increasing the range of metal silicate fractionation recorded in solar nebular processes they also have the greatest moderately volatile lithophile element depletions of any chondritic materials metal has compositional trends and zoning patterns that suggest a primitive condensation origin in contrast with metal from other chondrite groups cb chondrites as well as other cr clan chondrites have much heavier nitrogen higher 15n 14n than that in other chondrite groups the primitive characteristics of the cb chondrites suggest that they contain one of the best records of early nebular processes another chondrite grosvenor mountains 9555 1 is petrographically similar to the cb chondrites but its mineral and oxygen and nitrogen isotope compositions indicate that it formed from a different nebular reservoir

pb pb dating of individual chondrules from the cb a chondrite gujba assessment of the impact plume formation model the cb chondrites are metal rich meteorites with characteristics that sharply distinguish them from other chondrite groups their unusual chemical and petrologic features and a young formation age of bulk chondrules dated from the cba chondrite gujba are interpreted to reflect a single stage impact origin here we report high precision internal isochrons for four individual chondrules of the gujba chondrite to probe the formation history of cb chondrites and evaluate the concordancy of relevant short lived radionuclide chronometers all four chondrules define a brief formation interval with a weighted mean age of 4562 49 0 21 myr consistent with its origin from the vapor melt impact plume generated by colliding planetesimals formation in a debris disk mostly devoid of nebular gas and dust sets an upper limit for the solar protoplanetary disk lifetime at 4 8 0 3 myr finally given the well behaved pb pb systematics of all four chondrules a precise formation age and the concordancy of the mn cr hf w and i xe short lived radionuclide relative chronometers we propose that gujba may serve as a suitable time anchor for these systems

teleseismic investigation of the january 22 1988 tennant creek australia earthquakes the three january 22 1988 earthquakes are the largest to occur within the australian continent in 20 years and produced two colinear but discontinuous wnw trending scarps enclosing a shorter ene trending scarp teleseismic long period p and sh and short period p waves are used to constrain the locations and source parameters for the three events the third earthquake has a seismic moment 1019nm equal to that of the 1968 meckering event and most likely ruptured the southern of the wnw trending faults relative relocations suggest that the two smaller earthquakes initiated north or nw of the third event centroid depths are less than 6 km but most likely 3 to 4 km and source durations are 4 to 6s so it is probable that each event broke the surface all three earthquakes have predominantly thrust mechanisms and nodal planes that strike west to wnw consistent with faults dipping southward at 30 to 40 only the first has a nodal plane that could support a north dip for the ene trending fault as proposed by other researchers on the basis of ground deformation and preliminary aftershock locations however source directivity evident in the short period p waves and relocations are interpreted better if this event like the others ruptured a sw dipping fault plane the ene trending scarp is interpreted to be a tear fault in the hanging wall that may have acted as a barrier to slip on a single continuous sw dipping fault resulting in this unusual at least for australia sequence of three large similar earthquakes

the conditions of chondrule formation part i closed system abstract mixing was an important process in the early solar nebula and is often used as an argument to explain the compositional scatter among chondrules mm sized once molten silicate spherules in chondritic meteorites if it is hypothesized that chondrules only acted as closed systems and the scatter in chondrule bulk chemical compositions is only the result of mixing heterogeneous precursor grains the basic components of chondrules it is in turn possible to determine the sizes of the precursor grains using statistical calculations in order to reproduce the observed compositional scatter in chondrules not more than 10 precursor grains should contribute to a single chondrule each with a diameter of several 100 m this finding has important implications for the conditions of chondrule formation and replaces the so far widely accepted model that chondrules formed from fine grained dust balls chondrules rather formed from coarse grained precursor aggregates with variable amounts of m fine matrix material as a consequence only chondrite matrix or interstellar material winnows as precursor material large grains of variable composition serving as precursor grains must have been formed prior to chondrule formation chondrules probably have not been their immediate precursors as only 1 2 chondrule recycling steps would have homogenized bulk chondrule compositions chondrule recycling can therefore only have occurred to a limited extent chondrule formation needed at least three steps 1 production of large and heterogeneous chondrule precursor grains 2 agglomeration of large precursor grains and fine grained precursors into aggregates 3 formation of chondrules during transient heating events al rich chondrules can in this context be explained by the admixture of cais to either chondrule precursors or a population of existing chondrules

a nebula setting as the origin for bulk chondrule fe isotope variations in cv chondrites abstract we combined micro computer tomography with fe and si isotope measurements of mokoia allende and grosnaja chondrules ten mokoia chondrules contain 0 9 to 11 8 vol opaque phases metal sulfide and 6 allende chondrules contain 0 0 to 6 6 vol opaque phases hence the fe isotope composition of many chondrules is dominated by the fe isotope composition of their opaque phases we studied fe isotopes of 35 bulk chondrules the range is different for each of the three meteorites studied and largest for allende with 56 fe ranging from 0 82 to 0 37 six out of seven chondrules analysed for their si isotope composition in mokoia and grosnaja have similar 29 si of around 0 12 one anomalous chondrule in mokoia has a 29 si of 0 58 we exclude isotopically heterogeneous chondrule precursors and different isotopic chondrule reservoirs as the source of the observed fe isotope variation among bulk chondrules we conclude that the observed bulk chondrule fe isotope variation is the result of evaporation and re condensation processes in a nebula setting with high dust densities required to explain the comparatively low isotope fractionations subsequent parent body alteration slightly overprinted this pre accretionary fe isotope variation

estimates from altimeter data of barotropic rossby waves in the northwestern atlantic ocean abstract a dynamical model representing linear barotropic rossby waves is combined with geosat data from the northwest atlantic ocean the model is too simple to be very realistic in this complex area but the problem of combining any model with real data raises a number of issues that we address the combination method used is sequential estimation in the form of a filtering smoothing operation a fraction of the total signal variance 5 to 15 in the area over several spacecraft repeat cycles is demonstrated to be consistent with five rossby waves that the result is robust is demonstrated by recovering known signals added synthetically to the real data

molybdenum isotopic evidence for the origin of chondrules and a distinct genetic heritage of carbonaceous and non carbonaceous meteorites abstract nucleosynthetic isotope anomalies are powerful tracers to determine the provenance of meteorites and their components and to identify genetic links between these materials here we show that chondrules and matrix separated from the allende cv3 chondrite have complementary nucleosynthetic mo isotope anomalies these anomalies result from the enrichment of a presolar carrier enriched in s process mo into the matrix and the corresponding depletion of this carrier in the chondrules this carrier most likely is a metal and so the uneven distribution of presolar material probably results from metal silicate fractionation during chondrule formation the mo isotope anomalies correlate with those reported for w isotopes on the same samples in an earlier study suggesting that the isotope variations for both mo and w are caused by the heterogeneous distribution of the same carrier the isotopic complementary of chondrules and matrix indicates that both components are genetically linked and formed together from one common reservoir of solar nebula dust as such the isotopic data require that most chondrules formed in the solar nebula and are not a product of protoplanetary impacts allende chondrules and matrix together with bulk carbonaceous chondrites and some iron meteorites groups iid iiif and ivb show uniform excesses in 92 mo 95 mo and 97 mo that result from the addition of supernova material to the solar nebula region in which these carbonaceous meteorites formed non carbonaceous meteorites enstatite and ordinary chondrites as well as most iron meteorites do not contain this material demonstrating that two distinct mo isotope reservoirs co existed in the early solar nebula that remained spatially separated for several million years this separation was most likely achieved through the formation of the gas giants which cleared the disk between the inner and outer solar system regions parental to the non carbonaceous and carbonaceous meteorites the mo isotope dichotomy of meteorites provides a new means to determine the provenance of meteoritic and planetary materials and to assess genetic links between chondrites and differentiated meteorites

improving ocean tide predictions by using additional semidiurnal constituents from spline interpolation in the frequency domain the improvement in accuracy that can be obtained by increasing the number of constituents in the model at present used for tidal height corrections in the gdrs of satellite altimetric measurements is analysed by referring to the performance of the harmonic method in predicting tides at a selected number of locations in the world where observations of sea level variations are available given the interest in such improvements a way of extending the existing data set is proposed without the need to run a new model of the world s oceans the method relies on the concept of admittance world s oceans maps are derived for five additional constituents and the differences in predicted heights resulting from these improvements are evaluated

validity of ers 1 altimeter corrections sea surface height ssh observations from satellite altimeter are subjected to various types of environmental and geophysical errors to get the small amplitude of the order of a few centimeters dynamic oceanographic signals from altimeters effects due to these errors have to be corrected the validity of each of the correction terms to the ers 1 altimeter measurements have been studied most of the corrections reduced the variance and have thus been found to be effective altimetric corrections

the uluru ayers rock australia earthquake of 28 may 1989 abstract at 02 hr 55 min 21 sec utc on 28 may 1989 a richter m l 5 6 earthquake occurred in central australia in crystalline basement beneath the southern margin of the amadeus basin near mt olga and uluru ayers rock in the northern territory it had a well constrained focal depth of 31 km which explains why no surface faulting was discovered it is the deepest earthquake known to have occurred in australia prior to 1992 the largest to have been recorded in the region and had no observed foreshocks or aftershocks the earthquake was felt over a radius of 220 km and caused minor damage at yulara the fault plane solution indicates almost pure thrust faulting with a pressure axis striking n 64 e

the origin and history of the metal and sulfide components of chondrules abstract fourteen siderophile and other non lithophile elements determined in 31 semarkona ll3 0 chondrules by neutron activation analysis are severely fractionated relative to lithophile elements their chondrule whole rock abundance ratios vary by factors of up to 1000 the mean ratio is 0 2 non refractory siderophile abundance patterns in ni rich chondrules are smooth functions of volatility and in ni poor chondrules patterns are more irregular refractory siderophile elements are often fractionated from ni they covary confirming the presence of a refractory metal component the chalcophile element se correlates with br and siderophile elements zinc is uniformly low and uncorrelated with other elements most metal and sulfide in chondrules was probably present in the solar nebula before chondrule formation most siderophile and chalcophile elements were in these materials some fe was also in silicates as were minor amounts of ni co au ge and possibly se the amount of metal formed by reduction during chondrule melting was minor the common metal component in chondrules is similar to and may be the same as the common component involved in the metal silicate fractionation of the ordinary chondrite groups chondrules are depleted in metal chiefly because they sampled metal poor precursor assemblages metal segregation during the molten period and subsequent loss was a minor process that may be responsible for most surface craters on chondrules

the lack of potassium isotopic fractionation in bishunpur chondrules in a search for evidence of evaporation during chondrule formation the mesostases of 11 bishunpur chondrules and melt inclusions in olivine phenocrysts in 7 of them have been analyzed for their alkali element abundances and k isotopic compositions except for six points all areas of the chondrules that were analyzed had 41k compositions that were normal within error typically 3 2s the six anomalous points are probably all artifacts experiments have shown that free evaporation of k leads to large 41k enrichments in the evaporation residues consistent with rayleigh fractionation under rayleigh conditions a 3 enrichment in 41k is produced by 12 loss of k the range of l chondrite normalized k al ratios a measure of the k elemental fractionation in the areas analyzed vary by almost three orders of magnitude if all chondrules started out with l chondrite like k abundances and the k loss occurred via rayleigh fractionation the most k depleted chondrules would have had compositions of up to 41k 200 clearly k fractionation did not occur by evaporation under rayleigh conditions yet experiments and modeling indicate that k should have been lost during chondrule formation under currently accepted formation conditions peak temperature cooling rate etc invoking precursors with variable alkali abundances to produce the range of k al fractionation in chondrules does not explain the k isotopic data because any k that was present should still have experienced sufficient loss during melting for there to have been a measurable isotopic fractionation if k loss and isotopic fractionation was inevitable during chondrule formation the absence of k isotopic fractionation in bishunpur chondrules requires that they exchanged k with an isotopically normal reservoir during or after formation there is evidence for alkali exchange between chondrules and rim matrix in all unequilibrated ordinary chondrites however melt inclusions can have alkali abundances that are much lower than the mesostases of the host chondrules which suggests that they at least remained closed since formation if it is correct that some or all melt inclusions remained closed since formation the absence of k isotopic fractionation in them requires that the k isotopic exchange took place during chondrule formation which would probably require gas chondrule exchange potassium evaporated from fine grained dust and chondrules during chondrule formation may have produced sufficient k vapor pressure for gas chondrule isotopic exchange to be complete on the timescales of chondrule formation alternatively our understanding of chondrule formation conditions based on synthesis experiments needs some reevaluation

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

origin of volatile element depletion among carbonaceous chondrites abstract compared to the composition of ci chondrites and the sun all other carbonaceous chondrites are variably depleted in volatile elements however the origin of these depletions and how they are related to volatile loss during high temperature processes within the solar nebula are unclear to better understand the processes that caused volatile element fractionations among carbonaceous chondrites we obtained mass dependent te isotopic compositions and te concentrations for a comprehensive set of samples from the major carbonaceous chondrite groups the chondrites exhibit well resolved inter group te isotope variations towards lighter isotopic compositions for increasingly volatile depleted samples the te isotopic compositions and concentrations are also correlated with the mass fraction of matrix and with nucleosynthetic e 54 cr anomalies combined these correlations indicate mixing between volatile rich isotopically heavy and 54cr rich ci like matrix with volatile poor isotopically light and 54cr poorer chondrules or chondrule precursors the te cr isotopic correlation suggests that all carbonaceous chondrites contain ci like matrix and that chondrules and this ci like matrix formed from isotopically distinct material originating from different regions of the disk the only samples plotting off the te cr correlation are cr chondrites indicating that cr chondrules formed from different precursor material than chondrules from other carbonaceous chondrites either because they formed at greater heliocentric distance and or at a later time plots of volatile element abundances versus matrix mass fraction reveal that chondrules chondrule precursors display ci chondritic ratios for volatile elements with 50 condensation temperatures below 750 k with an overall abundance of 0 13 ci mixing between these two components therefore naturally results in ci like ratios for these elements in all carbonaceous chondrites in spite of different degrees of volatile depletion a corollary of this observation is that the ci like ratios of volatile elements in the bulk silicate earth may result from the accretion of volatile depleted materials and do not require accretion of ci chondrites themselves

modal mineralogy of ci and ci like chondrites by x ray diffraction the ci chondrites are some of the most hydrated meteorites available to study making them ideal samples with which to investigate aqueous processes in the early solar system here we have used position sensitive detector x ray diffraction psd xrd to quantify the abundance of minerals in bulk samples of the ci chondrite falls alais orgueil and ivuna and the antarctic ci like chondrites y 82162 and y 980115 we find that alais orgueil and ivuna are dominated by a mixed serpentine saponite phyllosilicate 81 84 vol plus minor magnetite 6 10 sulphides 4 7 and carbonates 3 this reflects an extended period of aqueous alteration and the near complete transformation of anhydrous phases into a secondary mineral assemblage the similarity in total abundance of phyllosilicate suggests that the ci chondrites all experienced the same degree of aqueous alteration on the parent body in contrast y 82162 contains a highly disordered serpentine saponite phyllosilicate 68 vol sulphide 19 olivine 11 and magnetite 2 this mineralogy is distinct from that of the ci chondrites attesting to both a different starting mineralogy and alteration history the structure and relatively low abundance of the phyllosilicate and the high abundance of olivine are consistent with previous observations that y 82162 represents ci like material that following aqueous alteration suffered thermal metamorphism at temperatures 500 c similarly y 980115 contains disordered serpentine saponite 71 vol sulphide 19 olivine 8 and magnetite 2 confirming that it too is a thermally metamorphosed ci like chondrite we suggest that the ci like chondrites are derived from a different parent body than the ci chondrites which underwent short lived thermal metamorphism due to impacts and or solar radiation

kinetic stability of a melted iron globule during chondrule formation i non rotating model we have investigated the kinematics of the separation of iron globules from chondrules during chondrule formation a simple model which assumes that the system has no angular momentum was used to calculate the energy of a system with an iron globule and a chondrule the energies of three different states were calculated 1 a melted iron globule fully embedded in a melted chondrule 2 a melted iron globule on the surface of a melted chondrule and 3 a melted iron globule being separated from a melted chondrule we also calculated the lowest energy shape for a melted iron globule on the surface of a melted chondrule and compared our result with the shapes of four natural samples of chondrules and iron globules in thin sections the shapes were calculated using an assumed value for the interface energy between the four couples of melted chondrules and the iron globules and agree well with the natural shapes of chondrules and iron globules the results of our calculations show that the iron globules of these four samples would be strongly bound to the surface of the melted chondrule during chondrule formation and separation would be difficult if the iron globules had been on the surface of precursors of these chondrules our results also show that if these iron globules were initially inside and transported to the surface of the melted chondrule most of them would be ejected from the inside to outside because of surface tension forces as long as the energy losses due to viscous dissipation when the globules pass through the surface of melted chondrules were sufficiently small although further improvement of the model is required our results demonstrate that this ejection process may be responsible for the depletion of siderophile elements in natural chondrules

the selenium isotopic variations in chondrites are mass dependent implications for sulfide formation in the early solar system abstract element transfer from the solar nebular gas to solids occurred either through direct condensation or via heterogeneous reactions between gaseous molecules and previously condensed solid matter the precursors of altered sulfides observed in chondrites are for example attributed to reactions between gaseous hydrogen sulfide and metallic iron grains the transfer of selenium to solids likely occurred through a similar pathway allowing the formation of iron selenides concomitantly with sulfides the formation rate of sulfide however remains difficult to assess here we investigate whether the se isotopic composition of meteorites contributes to constrain sulfide formation during condensation stages of our solar system we present high precision se concentration and 82 78 se data for 23 chondrites as well as the first 74 78 se 76 78 se and 77 78 se data for a sub set of seven chondrites we combine our dataset with previously published sulfur isotopic data and discuss aspects of sulfide formation for various types of chondrites our se concentration data are within uncertainty to literature values and are consistent with sulfides being the dominant selenium host in chondrites our overall average 82 78 se value for chondrites is 0 21 0 43 n 23 2 s d or 0 14 0 21 after exclusion of three weathered chondrites n 20 2 s d these average values are within uncertainty indistinguishable from a previously published estimate for the first time however we resolve distinct 82 78 se between ordinary 0 14 0 07 n 9 2 s d enstatite 0 27 0 05 n 3 2 s d and ci carbonaceous chondrites 0 01 0 06 n 2 2 s d we also resolve a se isotopic variability among cm carbonaceous chondrites in addition we report on 74 78 se 76 78 se and 77 78 se values determined for 7 chondrites our data allow evaluating the mass dependency of the 82 78 se variations mass independent deficits ro excesses of 74se 76se and 77se are calculated relative to the observed 82se 78se ratios and were observed negligible this rules out poor mixing of nucleosynthetic components to account for the 82 78 se variability and implies that the mass dependent se isotopic variations were produced in a once homogeneous disk the mass dependent isotopic difference between enstatite and ordinary chondrites may reflect the contribution of a kinetic sulfidation process at anomalously high h2s h2se contents in the region of enstatite chondrite formation experimental studies showed that high h2s contents favor the formation of compact sulfide layers around metallic grains this decreases the reactive surface which tends to inhibit the continuation of the sulfidation reaction under these conditions sulfide growth likely occurs under isotopic disequilibrium and favors the trapping of light s and se isotopes in solids this hypothesis provides an explanation for our se isotope as well as for previously published s isotope data on the other hand high 82 78 se values in carbonaceous chondrites may result from sample heterogeneities generated by parent body aqueous alteration or could reflect the contribution of ices carrying photo processed se from the outer solar system

nature of volatile depletion and genetic relationships in enstatite chondrites and aubrites inferred from zn isotopes enstatite meteorites include the undifferentiated enstatite chondrites and the differentiated enstatite achondrites aubrites they are the most reduced group of all meteorites the oxygen isotope compositions of both enstatite chondrites and aubrites plot along the terrestrial mass fractionation line which suggests some genetic links between these meteorites and the earth as well for this study we measured the zn isotopic composition of 25 samples from the following groups aubrites main group and shallowater el chondrites eh chondrites and happy canyon impact melt breccia we also analyzed the zn isotopic composition and elemental abundance in separated phases metal silicates and sulfides of the eh4 el3 and el6 chondrites the different groups of meteorites are isotopically distinct and give the following values parts per thousand aubrite main group 7 08 delta zn 66 0 37 eh3 chondrites 0 15 delta zn 66 0 31 eh4 chondrites 0 15 delta zn 66 0 27 eh5 chondrites delta zn 66 0 27 0 09 n 1 el3 chondrites 0 01 delta zn 66 0 63 the shallowater aubrite 1 48 delta zn 66 2 36 el6 chondrites 2 26 delta zn 66 7 35 and the impact melt enstatite chondrite happy canyon delta zn 66 0 37 the aubrite pena blanca spring delta zn 66 7 0 parts per thousand and the el6 north west forrest delta zn 66 7 35 are the isotopically lightest and heaviest samples respectively known so far in the solar system in comparison the range of zn isotopic composition of chondrites and terrestrial samples 1 5 delta zn 66 1 parts per thousand is much smaller luck et al 2005 herzog et al 2009 eh and el3 chondrites have the same zn isotopic composition as the earth which is another example of the isotopic similarity between earth and enstatite chondrites the zn isotopic composition and abundance strongly support that the origin of the volatile element depletion between el3 and el6 chondrites is due to volatilization probably during thermal metamorphism aubrites show strong elemental depletion in zn compared to both eh and el chondrites and they are enriched in light isotopes delta zn 66 down to 7 04 parts per thousand this is the opposite of what would be expected if zn elemental depletion was due to evaporation assuming the aubrites started with an enstatite chondrite like zn isotopic composition evaporation is therefore not responsible for volatile loss from aubrites on earth zn isotopes fractionate very little during igneous processes while differentiated meteorites show only minimal zn isotopic variability it is therefore very unlikely that igneous processes can account for the large isotopic fractionation of zn in aubrites condensation of an isotopically light vapor best explains zn depletion and isotopically light zn in these puzzling rocks mass balance suggests that this isotopically light vapor carries zn lost by the el6 parent body during thermal metamorphism and that aubritcs evolved from an el6 like parent body finally zn isotopes suggest that shallowater and aubrites originate from distinct parent bodies

formation of solar nebula reservoirs by mixing chondritic components we determined proportions of type i reduced and type ii oxidized chondrules in ordinary chondrites oc and found linear relationships between chondrule abundances and chondrite bulk chemical and oxygen isotopic compositions similar relationships exist between bulk oxygen isotopic compositions of carbonaceous chondrites and modal abundances of their chondritic components matrix type i and type ii chondrules refractory calcium aluminium rich inclusions and amoeboid olivine aggregates these correlations can be used to predict the bulk oxygen isotopic composition of chondrites based on their petrology we can also define model isotopic compositions associated with each petrologic component which are not their current actual isotopic compositions due to alteration or mixing these compositions for refractory inclusions and chondrules plot close to a slope 1 line consistent with refractory inclusions ri forming from an early 16o rich gas the evolution of the gas to more 16o poor compositions possibly involving photodissociation and subsequent ice transport followed by chondrule formation our results open a new understanding of the oxygen 3 isotope space and explain the unique position of oc as well as the differences between h l and ll chondrites they indicate that major chemical and isotopic variations between chondritic reservoirs were established after chondrule and cai formation they may have some bearing on the formation of planetary reservoirs the 17o calculated for type i chondrules is appropriate for terrestrial planet progenitors consistent with their chemical similarity to earth mantle

petrographic constraints on the diversity of chondrule reservoirs in the protoplanetary disk abstract chondrules from different chondrite groups show characteristic properties including abundances of different chondrule textural types chondrule sizes oxygen isotope compositions chondrule bulk compositions and petrographic properties of type i and type ii chondrules including abundances of relict grains overall it can be argued that each chondrite group sampled a unique chondrule reservoir and that chondrite groups may represent fractions of larger reservoirs that are represented by chondrite classes these observations provide constraints for models of the early solar system in which it is necessary to establish multiple separate chondrule reservoirs and maintain them over extended time periods models for accretion of chondrite parent bodies must be able to account for localized accretion of chondrules that were formed in spatially or temporally separated reservoirs

the neodymium stable isotope composition of the silicate earth and chondrites abstract the non chondritic neodymium nd 142nd 144nd ratio of the silicate earth potentially provides a key constraint on the accretion and early evolution of the earth yet it is debated whether this offset is due to the earth being formed from material enriched in s process nd isotopes or results from an early differentiation process such as the segregation of a late sulfide matte during core formation collisional erosion or a some combination of these processes neodymium stable isotopes are potentially sensitive to early sulfide segregation into earth s core a process that cannot be resolved using their radiogenic counterparts this study presents the first comprehensive nd stable isotope data for chondritic meteorites and terrestrial rocks stable nd measurements were made using a double spike technique coupled with thermal ionisation mass spectrometry all three of the major classes of chondritic meteorites carbonaceous enstatite and ordinary chondrites have broadly similar isotopic compositions allowing calculation of a chondritic mean of 146 144nd 0 025 0 025 2 s d n 39 enstatite chondrites yield the most uniform stable isotope composition 146 144nd 26 ppm with considerably more variability observed within ordinary 146 144nd 72 ppm and carbonaceous meteorites 146 144nd 143 ppm terrestrial weathering nucleosynthetic variations and parent body thermal metamorphism appear to have little measurable effect on 146 144nd in chondrites the small variations observed between ordinary chondrite groups most likely reflect inherited compositional differences between parent bodies with the larger variations observed in carbonaceous chondrites being linked to varying modal proportions of calcium aluminium rich inclusions the terrestrial samples analysed here include rocks ranging from basaltic to rhyolitic in composition morb glasses and residual mantle lithologies all of these terrestrial rocks possess a broadly similar nd isotope composition giving an average composition for the bulk silicate earth of 146 144nd 0 022 0 034 n 30 in the samples here magmatic differentiation appears to only have an effect on stable nd in highly evolved magmas with heavier 146 144nd values observed in samples with 70 wt sio2 the average stable nd isotope composition of chondrites and the bulk silicate earth are indistinguishable at the 95 confidence level however mantle samples do possess variable stable nd isotope compositions 146 144nd 75 ppm with an average 146 144 nd value of 0 008 if these heavier values represent the true composition of pristine mantle then it is not possible to completely rule out some role for core formation in accounting for some of the offset between the mantle and chondrites overall these results indicate that the mismatch of 142nd between the earth and chondrites is best explained by a higher proportion of s process nd in the earth rather than partitioning into sulfide or s rich metal in the core

gallium isotopic evidence for the fate of moderately volatile elements in planetary bodies and refractory inclusions abstract the abundance of moderately volatile elements such as zn and ga show variable depletion relative to ci between the earth and primitive meteorite chondrites parent bodies furthermore the first solar system solids the calcium aluminum rich inclusions cais are surprisingly rich in volatile element considering that they formed under high temperatures here we report the ga elemental and isotopic composition of a wide variety of chondrites along with five individual cais to understand the origin of the volatile elements and to further characterize the enrichment of the volatile elements in high temperature condensates the 71 ga permil deviation of the 71ga 69ga ratio from the ga ipgp standard of carbonaceous chondrites decreases in the order of ci cm co cv and is inversely correlated with the al ga ratio this implies that the ga budget of the carbonaceous chondrites parent bodies were inherited from a two component mixing of a volatile rich reservoir enriched in heavy isotope of ga and a volatile poor reservoir enriched in light isotope of ga calcium aluminum rich inclusions are enriched in ga and zn compared to the bulk meteorite and are both highly isotopically fractionated with 71 ga down to 3 56 and 66 zn down to 0 74 the large enrichment in the light isotopes of ga and zn in the cais implies that the moderately volatile elements were introduced in the cais during condensation in the solar nebula as opposed to secondary processing in the meteorite parent body and supports a change in gas composition in which cais were formed