the fine grained matrix of the semarkona ll3 0 ordinary chondrite an induced thermoluminescence study to investigate the nature origin and history of the fine grained matrix in semarkona and develop techniques suitable for small samples we have measured the induced thermoluminescence properties of six matrix samples 10 m to 400 m in size the samples had tl sensitivities comparable with 4 mg of bulk samples of type 3 2 3 4 ordinary chondrites which is very high relative to bulk semarkona the other induced tl properties of these samples tl peak temperatures and tl peak widths distinguish them from other ordinary chondrite samples where the tl is caused by feldspar cathodoluminescence images and other data suggest that the cause of the luminescence in the semarkona fine grained matrix is forsterite in some respects the matrix tl data resemble that of semarkona chondrules in which the phosphor is forsterite and terrestrial forsterites from a variety of igneous and metamorphic environments however differences in the tl peak temperature versus tl peak width relationship between the matrix samples and the other forsterites suggest a fundamentally different formation mechanism we also note that forsterite appears to be a major component in many primitive materials such as nebulae cometary dust and stardust particles

late quaternary fluvial dynamics and landscape evolution at the lower shulaveris ghele river southern caucasus the southern caucasus was intensively settled through the neolithic period to present studies of late quaternary fluvial dynamics and landscape development at the lower shulaveris ghele river in southeastern georgia aid understanding of the quaternary history of this region our studies show that following river aggradation to form a fan shaped alluvial surface during the late pleistocene fluvial sedimentation shifted west leaving a fan surface subject only to local fluvial and colluvial processes as well as late neolithic settlement at about 6 ka the river avulsed to the east and eroded some late neolithic settlements occupying the eastern portion of the fan the avulsion was followed by 3 distinct episodes of aggradation at about 6 ka 3 2 ka and since 1 0 ka no such aggradation is evident in the early holocene regional holocene fluvial activity in this area was apparently influenced by vegetation dynamics possibly controlled by regional climatic and or anthropogenic factors and significantly differs from the eastern mediterranean region all late neolithic settlements were originally built far from an active river possibly indicating late neolithic water management systems

a chondrule origin for dusty relict olivine in unequilibrated chondrites we address the origin of dusty metal bearing relict olivine grains in chondrules it has been suggested previously that these grains may be either primitive condensates or derived from a previous generation of chondrules in this paper we infer the original composition of dusty olivine grains before they were reduced and examine the possibility that they were derived from a previous generation of chondrules original compositions of dusty grains including their estimated initial feo contents and their minor element contents match closely with compositions of olivines from chondrules in unequilibrated chondrites in addition the cores of some dusty grains are unaltered and the compositions of these cores are also consistent with a chondrule origin therefore we conclude that a derivation from a previous generation of chondrules is a plausible origin for these relicts although alternative origins such as condensates or interstellar grains cannot be ruled out on the basis of the available data chondrules are an obvious source and we suggest that this is the most likely interpretation if this is the case it is additional evidence for the importance of recycling of chondrule material in the chondrule forming region

stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

origin of chondrule rims and interchondrule matrices in unequilibrated ordinary chondrites optical microscopy electron probe microanalysis scanning electron microscopy and analytical transmission electron microscopy were used to study the interchondrule matrix and opaque chondrule rims in bishunpur krymka semarkona chainpur all ll3 tieschitz and sharps both h3 the size distribution of grains in matrix in bishunpur obeys a power law rims around chondrules tend to be finer grained than matrix and may be layered all rims and matrices studied contain clasts of forsteritic olivine and low ca pyroxene in bishunpur the clasts may be cemented by amorphous glue rich in normative albite and partly altered to smectite rims in krymka sharps chainpur and tieschitz have a densely packed olivine groundmass with a grain size of about 0 1 m in krymka groundmass olivine is fo20 30 and forms interlocking dendrites various fe oxides are present in rims and matrices grain size distribution and chemical data indicate that clastic olivines and pyroxenes are derived from chondrules from analyses matrices rims in the ll group apparently are enriched in a feldspathic component tieschitz rims are slightly enriched but here the feldspathic component is present as white matrix sharps rims are not enriched in a feldspathic component opaque interchondrule matrices and chondrule rims probably formed from the products of fragmentation of chondrules partly induced by contraction of protopyroxene on inversion to clinopyroxene fragmented silica rich chondrule mesostases reacted with fe oxides and na to form the groundmass of fayalitic olivine and feldspathic glue a low temperature nebular or pre solar component is limited to 3 vol of each meteorite so equilibrium condensate was not the carrier of volatiles such as tl and bi

chemical and physical studies of type 3 chondrites ix thermoluminescence and hydrothermal annealing experiments and their relationship to metamorphism and aqueous alteration in type 3 3 ordinary chondrites samples of four type 3 chondrites have been annealed at 400 850 c and 0 77 1 kbar for 10 500 h in the presence of various amounts of water 0 10 wt and sodium disilicate 0 2 molal and their thermoluminescence properties measured after annealing for 20 h at temperatures 600 c the tl sensitivity of the samples increased by factors of up to 40 after annealing at 800 c when both high and low forms were present originally the low form was destroyed preferentially we suggest that these data are consistent with the tl metamorphism trends observed in type 3 2 chondrites being due to the formation of feldspar with structural details being dependent on formation temperature by the devitrification of chondrule glass during metamorphism for types 3 2 the tl data are equally consistent with these types experiencing lower levels of metamorphism than the higher types or with type 3 0 being produced from higher types by aqueous alteration the presence of water with non terrestrial d h ratios and petrographic evidence for aqueous alteration in semarkona lead us to favour the aqueous alteration hypothesis

photomosaics of the cathodoluminescence of 60 sections of meteorites and lunar samples 1 cathodoluminescence cl petrography provides a means of observing petrographic and compositional properties of geological samples not readily observable by other techniques we report the low magnification cl images of 60 sections of extraterrestrial materials the images we report include ordinary chondrites including type 3 ordinary chondrites and gas rich regolith breccias enstatite chondrites co chondrites and a cm chondrite eucrites and a howardite lunar highland regolith breccias and lunar soils the cl images show how primitive materials respond to parent body metamorphism how the metamorphic history of el chondrites differs from that of eh chondrites how dark matrix and light clasts of regolith breccias relate to each other how metamorphism affects eucrites the texture of lunar regolith breccias and the distribution of crystallized lunar spherules lunar chondrules and how regolith working affects the mineral properties of lunar soils more particularly we argue that such images are a rich source of new information on the nature and history of these materials and that our efforts to date are a small fraction of what can be done

the vicencia meteorite fall a new unshocked s1 weakly metamorphosed 3 2 ll chondrite the vicencia meteorite a stone of 1 547 kg fell on september 21 2013 at the village borracha near the city of vicencia pernambuco brazil it was recovered immediately after the fall and our consortium study showed it to be an unshocked s1 ll3 2 ordinary chondrite the ll group classification is based on the bulk density 3 13 g cm 3 the chondrule mean apparent diameter 0 9 mm the bulk oxygen isotopic composition delta 17 o 3 768 pm0 042 text o mkern 5mu mkern 3mu text oo delta 18 o 5 359 pm0 042 text o mkern 5mu mkern 3mu text oo delta 17 o 0 981 pm 0 020 text o mkern 5mu mkern 3mu text oo the content of metallic fe ni 1 8 vol the co content of kamacite 1 73 wt the bulk contents of the siderophile elements ir and co versus au and the ratios of metallic fe 0 total iron 0 105 versus total fe mg 1 164 and of ni mg 0 057 versus total fe mg the petrologic type 3 2 classification is indicated by the beautifully developed chondritic texture the standard deviation 0 09 versus mean cr 2 o 3 content 0 14 wt of ferroan olivine the tl sensitivity and the peak temperature and peak width at half maximum the cathodoluminescence properties of chondrules the content of trapped 132 xe tr 0 317 10 8 cm 3 stp g 1 and the raman spectra for organic material in the matrix the cosmic ray exposure age is 72 ma which is at the upper end of the age distribution of ll group chondrites the meteorite is unusual in that it contains relatively large up to nearly 100 m in size secondary fayalite grains defined as olivine with fa textgreater 75 large enough to allow in situ measurement of oxygen and mn cr isotope systematics with sims its oxygen isotopes plot along a mass dependent fractionation line with a slope of 0 5 and delta 17o of 4 0 pm 0 3 text o mkern 5mu mkern 3mu text oo and are similar to those of secondary fayalite and magnetite in the unequilibrated chondrites eet 90161 met 96503 and ngawi these data suggest that secondary fayalite in vicencia was in equilibrium with a fluid with a delta 17 o of 4 text o mkern 5mu mkern 3mu text oo consistent with the composition of the fluid in equilibrium with secondary magnetite and fayalite in other unequilibrated ordinary chondrites secondary fayalite and the chondrule olivine phenocrysts in vicencia are not in isotopic equilibrium consistent with low temperature formation of fayalite during aqueous alteration on the ll parent body that alteration as dated by the 53 mn 53 cr chronology age of secondary fayalite took place 4 0 1 4 1 1 ma after formation of cv cais when anchored to the quenched angrite d orbigny

generation of abnormal trace element abundances in antarctic eucrites by weathering processes abstract based on rees antarctic eucrites can be divided into two groups those showing normal trace element characteristics e g similar to juvinas and those showing abnormal trace element abundances many antarctic eucrite polymict eucrite and basaltic clast samples show the abnormal trace element abundances with ree patterns exhibiting positive ce anomalies sometimes negative ce anomalies positive eu anomalies and low abundances of the remainder of the rees with the lrees generally being at lower relative abundances than the hrees most samples of crystalline clasts from the polymict eucrites lew85300 lew85302 and lew85303 show the abnormal patterns while the glassy matrixes of these meteorites show normal patterns exterior samples generally show more abnormal patterns larger anomalies greater depletions than interior samples from the same meteorites comparison of all basaltic eucrite literature data combined with our data shows that positive and negative ce anomalies and positive eu anomalies are found in about 61 of antarctic eucrite analyses and are virtually unknown in non antarctic eucrite analyses further positive ce anomalies and positive eu anomalies are commonly associated with antarctic eucrites having low ree concentrations consideration of mineral melt partition coefficients shows that it is unlikely that ce anomalies are magmatic features from the hed parent body cerium anomalies on earth are generally restricted to the weathering zone where the relative ease of oxidizing ce to the 4 state allows for fractionation of ce from the 3 rees we believe the unusual ree patterns of abnormal antarctic eucrites arise from weathering effects generated in or on the antarctic ice our suggested scenario involves formation of melt water and its equilibration with the atmosphere which promotes dissolution of ree rich phosphates and oxidation of ce tetravalent ce can then be fractionated from the trivalent ree in solution the details of the weathering process are unclear and will require detailed chemical and sem investigations of eucrites for their elucidation we predict that rapidly chilled eucrites with glassy rather than crystalline mesostases will be more likely to survive the antarctic environment without alteration of their ree patterns occasional s se and k enrichments are likely due to weathering in the antarctic environment as well but these enrichments are not well correlated with ce anomalies

thermoluminescence and compositional zoning in the mesostasis of a semarkona group a1 chondrule and new insights into the chondrule forming process a large group a1 porphyritic olivine chondrule in the semarkona ll3 0 chondrite with induced thermoluminescence tl and compositional zoning in its mesostasis has been discovered the chondrule has ca rich and fe poor olivine cao 0 36 0 40 wt fa0 3 0 5 and its mesostasis is highly anorthite normative 52 5 wt the chondrule shows an intense induced tl peak at 300 c with a half width of 180 c the induced tl in the 40 440 c range increases monotonically by a factor of 6 from center to rim while sio2 na2o and mno increase by factors of 1 1 3 6 and 6 respectively the spectrum of the induced tl over the 200 350 c range i e a dominant peak at 570 nm with a half width of about 100 nm and the mn tl correlation suggest mn activated plagioclase is an important constituent of the refractory mesostases in group a1 chondrules the zoning may reflect fractional crystallization soret diffusion transport of volatiles into the chondrule by aqueous alteration a zoned precursor reduction of precursor dust aggregate or recondensation of volatiles lost during chondrule formation the first four possibilities seem unlikely explanations for the zoning of the mesostasis but both reduction of precursor dust aggregate and recondensation of volatiles seem to have played significant roles to the formation of the zoning reducing conditions at high temperatures are suggested to have prevailed during the formation of group a1 chondrules

trace element contents of chondrule rims and interchondrule matrix in ordinary chondrites abstract the abundances of forty elements have been measured in the rims and matrices of the unequilibrated ordinary chondrites semarkona bishunpur chainpur and krymka the rims appear to be mixtures of matrix like material and material that was volatilized during chondrule formation iron silicon manganese and copper all appear to have behaved as volatiles during chondrule formation and their enrichments are generally confined to the rims suggesting recondensation of these elements was rapid and localized this is supported by petrologic observations that show many chondrules were still partially molten or plastic when the rims accreted some rims also exhibit a decrease in both their feo content and the degree of mineral re equilibration away from the chondrule the alkali metals are enriched in both the rims and matrices the alkalis may have recondensed onto the matrix as well as the rims but their mobility is such that they have probably undergone extensive redistribution after accretion some na may even have been able to diffuse back into chondrules either during chondrule cooling or during metamorphism alteration most refractory lithophiles are depleted with respect to a1 in the rims and matrices in all four uocs these depletions are probably due to postaccretional redistribution of these elements into phosphates and other secondary minerals that form in and around metal sulfide grains the matrix is probably composed of chondrule fragments and processed nebular dust but the presence of carbonaceous presolar grains in the matrix indicates that there must be unprocessed presolar silicates present too on average the presolar silicates presumably have a ci like composition but a ci like signature is not seen in the matrix compositions simple estimates suggest that the abundances of carbonaceous presolar grains are consistent with there being at most 10 wt o presolar silicates present in uoc matrix which would be hard to detect in this study

north atlantic influence on holocene flooding in the southern greater caucasus in the context of global climate change flooding becomes an increasingly serious threat to modern societies and future flooding can only be understood using long term geological flood records als

petrology of feo poor porphyritic pyroxene chondrules in the semarkona chondrite abstract the mineralogy and petrology of feo poor porphyritic pyroxene and olivine rich chondrules in the semarkona ll3 0 chondrite are described in detail in an extension of the textural classification scheme these chondrules are designated types iab and ib in type iab chondrules the proportion of olivine phenocrysts is between 20 80 and in type ib chondrules olivine constitutes

glacial interglacial changes in southern africa compound specific δ13c land plant biomarker and pollen records from southeast atlantic continental margin sediments this is part 2 of a study examining southwest african continental margin sediments from nine sites on a north south transect from the congo fan 4 s to the cape basin 30 s representing two glacial mis 2 and 6a and two interglacial stages mis 1 and 5e contents distribution patterns and molecular stable carbon isotope signatures of long chain n alkanes c27 c33 and n alkanols c22 c32 as indicators of land plant vegetation of different biosynthetic types were correlated with concentrations and distributions of pollen taxa in sediments of the same time horizons selected single pollen type data reveal details of vegetation changes but the overall picture is best illustrated by summing pollen known to predominantly derive from c4 plants or c4 plus cam plants the c4 plant signals in the biomarkers are recorded in the 13c data and in the abundances of c31 and c33n alkanes and the c32n alkanol calculated clusters of wind trajectories for austral summer and winter situations for the holocene and the last glacial maximum afford information on the source areas for the lipids and pollen and their transport pathways to the ocean this multidisciplinary approach provides clear evidence of latitudinal differences in leaf wax lipid and pollen composition with the holocene sedimentary data paralleling the current major phytogeographic zonations the northern sites congo fan area and northern angola basin get most of their terrestrial material from the congo basin and the angolan highlands dominated by c3 plants airborne particulates derived from the western and central south african hinterland dominated by deserts semideserts and savannah regions are rich in organic matter from c4 plants as can be expected from the present and glacial positions of the phytogeographic zones the carbon isotopic signatures of n alkanes and n alkanols both become isotopically more enriched in 13c from north to south in the northern part of the transect the relative importance of c4 plant indicators is higher during the glacials than in the interglacials indicating a northward extension of arid zones favoring grass vegetation in the south where grass rich vegetation merges into semidesert and desert the difference in c4 plant indicators is small

plant wax d h ratios in the southern european alps record multiple aspects of climate variability we present a younger dryas holocene record of the hydrogen isotopic composition of sedimentary plant waxes d wax from the southern european alps lake ghirla n italy to investigate its sensitivity to climatic forcing variations in this mid latitude region 45 n a modern altitudinal transect of d values of river water and leaf waxes in the lake ghirla catchment is used to test present day climate sensitivity of d wax while we find that altitudinal effects on d wax are minor at our study site temperature precipitation amount and evapotranspiration all appear to influence d wax to varying extents in the lake sediment record d wax values vary between 134 and 180 over the past 13 kyr the long term holocene pattern of d wax parallels the trend of decreasing temperature and is thus likely forced by the decline of northern hemisphere summer insolation shorter term fluctuations in contrast may reflect both temperature and moisture source changes during the cool younger dryas and little ice age lia periods we observe unexpectedly high d wax values relative to those before and after we suggest that a change towards a more d enriched moisture source is required during these intervals in fact a shift from northern n atlantic to southern n atlantic western mediterranean sea sources would be consistent with a southward migration of the westerlies with climate cooling prominent d wax fluctuations in the early and middle holocene are negative and potentially associated with temperature declines in the late holocene 4 kyr bp excursions are partly positive as for the lia suggesting a stronger influence of moisture source changes on d wax variation in addition to isotopic fractionations of the hydrological cycle changes in vegetation composition in the length of the growing season and in snowfall amount provide additional potential sources of variability although we cannot yet quantitatively assess these in the paleo record we conclude that while our d wax record from the alps does contain climatic information it is a complicated record that would require additional constraints to be robustly interpreted this also has important implications for other water isotope based proxy records of precipitation and hydro climate from this region such as cave speleothems

plant wax δd values record changing eastern mediterranean atmospheric circulation patterns during the 8 2 kyr b p climatic event abstract throughout the holocene the climate of the mediterranean region has been strongly influenced by variability in the atmospheric circulation of the high and low latitudes a prominent example for such holocene climate perturbations is the 8 2 kyr b p climatic event reorganization of northern hemisphere atmospheric circulation patterns resulted in variations of temperature and precipitation distribution across the mediterranean the effects of changing high and low latitude atmospheric circulation on mediterranean climate in relation to the 8 2 kyr b p climatic event are however not well understood here we present a high resolution record of stable hydrogen isotope composition of plant wax n alkanes dwax across the 8 2 kyr b p climatic event from the tenaghi philippon peat deposit ne greece in order to characterize patterns of precipitation and changes in atmospheric circulation in the eastern mediterranean region our record reveals pronounced changes in dwax that correlate closely with previously published palynological data a long term decline in dwax values characterizes the lower part of the section the 8 2 kyr b p climatic event itself is connected to two distinct positive dwax excursions a minor shift in dwax around 8 2 kyr b p and a major shift in dwax between ca 8 1 and 8 0 kyr b p the upper part of the section shows a progressive trend towards higher dwax values we link shifts in dwax to changes in mediterranean air mass trajectories supplying precipitation to ne greece caused by variations in the relative contributions of northerly derived d depleted moisture and southerly derived d enriched moisture possible control mechanisms for alternating air mass trajectories include changes in the influence of the siberian high and differences in the influence of the african and asian monsoon circulation on anticyclonic conditions in the mediterranean region as well as regional inflow of moist air masses from the aegean sea

a 250 ka leaf wax δd record from a loess section in darai kalon southern tajikistan abstract the climate of sw central asia is influenced by strong precipitation seasonality with dry summers and winter spring precipitation delivered by mid latitude westerlies due to its geographic position sw central asia is a key locality for identifying fluctuations of westerlies siberian high and sw monsoon yet there is only limited information on the pleistocene climate history in sw central asia here we use plant wax biomarkers and their hydrogen isotope d composition from a loess section in darai kalon southern tajikistan to reconstruct environmental conditions of the past 250 thousand years ka we focus on the hydrogen isotope composition of long chain n alkanes dalk and long chain n carboxylic acids dcarb to reconstruct changes in the hydrological system moreover we infer information about past vegetation changes from proxies based on the relative abundance of these compounds results show that during glacials grasses dominated whereas during interglacials arboreal species prevailed these changes in vegetation follow the dominant glacial interglacial variability visible in the loess stratigraphy our results are in line with decreased precipitation during glacials as a result of a more extensive siberian high isotope measurements reveal a close relation of dalk and dcarb with insolation controlled by 20 ka cycles of orbital precession that is distinct from the glacial interglacial variability of the loess stratigraphy depleted enriched dalk and dcarb values coincide with low high winter spring insolation the precessional mode of our isotope records is likely influenced by variations in the precipitation seasonality between winter and spring precipitation caused by insolation induced temperature changes in comparison with speleothem records along the westerly path our results further indicate that the winter westerly storm tracks did not extend to the east of the tian shan during the last two glacial cycles

the induced thermoluminescence and thermal history of plagioclase feldspars feldspars are a common component in igneous and metamorphic rocks most feldspars exhibit luminescence and this has proved useful in a number of mineralogical applications in this paper we concentrate on the thermoluminescence tl properties of feldspar or the luminescence produced when a sample of feldspar is heated we determined the induced tl properties of four feldspars of various compositions in their natural states and after heating and we compared the tl data with structural changes as determined by x ray diffraction the major tl peak at 120 240 c in the tl glow curve a plot of light intensity against temperature varies significantly among feldspar bearing samples meteorites and lunar samples with slow cooling histories of 10 c my as determined by independent methods have induced tl peak temperatures of 120 c while samples with fast cooling histories 100 c my have induced tl peak temperatures of 220 c this variation in tl peak temperature can be reproduced by heating the present feldspar samples meteorites and lunar samples prior to the tl measurement most of the present samples in their natural state had tl peak temperatures of 120 c heating below 750 c in the laboratory caused no change in tl peak temperatures or the structural disorder of the feldspar while heating 750 c caused tl peak temperatures to move to 220 c and disordered the feldspar structure we suggest that induced tl peak temperature in feldspar is influenced by the degree of al si ordering in the feldspar thus induced tl peak temperature can be used as an indicator of cooling rate for igneous and metamorphic rocks

the matrices of unequilibrated ordinary chondrites implications for the origin and history of chondrites abstract the matrices of sixteen unequilibrated ordinary chondrites all witnessed falls were studied microscopically in transmitted and reflected light and analyzed by electron microprobe selected specimens were also studied by scanning electron microscopy these studies indicate that the fine grained opaque silicate matrix of type 3 unequilibrated chondrites is compositionally mineralogically and texturally distinct from the chondrules and chondrule fragments and may be the low temperature condensate proposed by larimer and anders 1967 1970 examination of the matrices of unequilibrated chondrites also shows that each meteorite has been metamorphosed with the alteration ranging in intensity from quite mild where the matrix has been only slightly altered to a more severe metamorphism that has completely recrystallized the opaque matrix most of the metamorphic changes in the matrix occurred without significant effects on the compositions or textures of the chondrules the metamorphic alteration probably resulted from a combination of processes including thermal metamorphism and the passage of shock waves the present appearance of each unequilibrated chondrite is a result of the particular temperature and pressure conditions under which it and its components formed plus the subsequent metamorphic alteration it experienced

constraints on the formation environment of two chondrule like igneous particles from comet 81p wild 2 using chemical and petrologic evidence and modeling we deduce that two chondrule like particles named iris and callie from stardust cometary track c2052 12 74 formed in an environment very similar to that seen for type ii chondrules in meteorites iris was heated near liquidus equilibrated and cooled at 100 c hr and within 2 log units of the iw buffer with a high partial pressure of na such as would be present with dust enrichments of 103 there was no detectable metamorphic nebular or aqueous alteration in previous work ogliore et al 2012 reported that iris formed late 3 myr after cais assuming 26al was homogenously distributed and was rich in heavy oxygen iris may be similar to assemblages found only in interplanetary dust particles and stardust cometary samples called kool particles callie is chemically and isotopically very similar but not identical to iris

dynamic cyrstallization of chondrule melts of porphyritic olivine composition textures experimental and natural abstract melts of the same composition as has been defined for porphyritic olivine chondrules have been crystallized under controlled cooling conditions dynamic crystallization the full range of textures observed in such chondrules has been duplicated in the experimentally produced analogs the primary controlling factor in producing this range of textuures is the heterogeneous nucleation behavior in general if nuclei are present when cooling begins growth starts immediately at low degrees of supercooling and porphyritic textures result the shapes of the phenocyrsts depend on the growth rate which in turn depends on the cooling rate with high nucleation densities and modest to low cooling rates the textures are microporphyritic with generally equant euhedral phenocrysts as the nucleatio density decreases the phenocrysts become larger and as the cooling rate increases they become increasingly skeletal if nuclei are not present when cooling begins growth is delayed until subcritical sized embryos graduate to supercritical nuclei growth usually begins at some significant degree of supercooling depending on the cooling rate and how long it takes the embryos to become nuclei the shapes of the crystals depend on the degree of supercooling when growth is initiated and on the subsequent cooling rate the resulting textures vary from plate dendrites barred olivine chondrules to randomly oriented elongated skeletal crystals as the degree of supercooling and cooling rates decreases the results of a matrix of experiments set limits on the maximum melting temperatures of chondrule forming materials and the subsequent cooling rates based primarily on crystal shape the porphyritic textures develop best for this composition at melting temperatures less than 1590 c and cooling rates near 100 c hr and definitely less than 1000 c hr at cooling rates significantly less than 100 c hr the phenocrysts are generally larger than observed in chondrules and as cooling rates approach 1000 c hr they become more skeletal barred olivine chondrule textures form best from materials melted at higher temperatures and cooling rates in the range 1000 to 3000 c hr

the potential of leaf wax biomarkers from fluvial soil sediment sequences for paleovegetation reconstructions upper alazani river central southern greater caucasus georgia abstract leaf wax derived long chain n alkanes are increasingly used for paleovegetation reconstructions but have hardly been applied to fluvial sediments so far however such analyses could significantly enhance knowledge of the former vegetation in many regions devoid of non fluvial sediment archives therefore this exemplary study investigates potentials and challenges of n alkane biomarker analyses in a fluvial sediment paleosol sequence fsps along the upper alazani river in the central southern greater caucasus generally fsps contain two different biomarker signals a catchment signal in fluvial sediments and a local in situ signal in intercalated paleosols this allows paleovegetation reconstructions for both catchment area and sampling site however several archive related challenges exist concerning the catchment signal from fluvial sediments i this could be biased by different vegetation zones land use histories in subcatchments ii long term pedogenesis on the slopes or intermediate sediment storage in the catchment could have caused a time lag between biomarker formation and sedimentation iii taphonomic processes could have biased the preserved n alkane pattern iv there could be petrogenically inherited or in river produced n alkanes v the signal could be overprinted by post sedimentary processes concerning the local paleosol signal this could be biased by inherited catchment derived biomarkers or by taphonomic processes these factors are thoroughly discussed for the investigated fsps with respect to paleovegetation patterns our investigations gave the following results i leaf waxes in fluvial sediments deposited prior to around the pleistocene holocene transition and between ca 5 and 1 7 cal ka bp are indicative of more deciduous trees shrubs in the catchment compared with the other periods that were dominated by grasses herbs considering a possible time lag of ca 1 4 ka between biomarker formation and deposition this indicates delayed holocene reforestation in the catchment compared with western and central europe in agreement with regional pollen studies the subsequent decline of deciduous trees shrubs could be linked to human activity in the catchment during the late holocene ii leaf waxes in floodplain paleosols indicate local grass herb dominance throughout the holocene which is possibly caused by long lasting local human activity

recurring large deep earthquakes in hindu kush driven by a sinking slab hindu kush subduction zone produces large intermediate depth earthquakes within a small volume every 10 15 years here we study the last three m 7 events within the cluster and find complex and diverse rupture processes however their main subevents appear to recur on the same fault patch dipping 70 to the south this recurrence requires an average of 9 6 cm yr slip rate on the patch much higher than the 1 cm yr surface convergence rate measured geodetically the high slip rate is likely caused by significant slab internal deformation such as localized slab stretching necking we infer that the hindu kush subducted slab below 210 km is sinking through the mantle at a vertical rate of 10 cm yr

chemical and physical studies of type 3 chondrites iii chondrules from the dhajala h3 8 chondrite abstract fifty eight chondrules were separated from the dhajala h3 8 chondrite and their thermoluminescence properties were measured chips from 30 of the chondrules were examined petrographically and with electron microprobe techniques the bulk compositions of 30 chondrules were determined by the fused bead technique porphyritic chondrules especially 5 which have particularly high contents of mesostasis tend to have higher tl mass normalized than non porphyritic chondrules significant correlations between log tl and the bulk cao al 2 o 3 and mno content of the chondrules and between log tl and the cao al 2 o 3 sio 2 and normative anorthite content of the chondrule glass indicate an association between tl and the abundance and composition of mesostasis unequilibrated chondrules i e those whose olivine is compositionally heterogeneous and high in ca have low tl whereas equilibrated chondrules have a wide range of tl depending on their chemical and petrographic properties we suggest that the tl level in a given chondrule is governed by its bulk composition which largely determined the abundance and composition of constituent glass and by metamorphism which devitrfied the glass in those chondrules with high ca glass to produce the tl phosphor we also suggest that one reason why certain chondrules in type 3 ordinary chondrites are unequilibrated while others are equilibrated is that the mesostasis of the unequilibrated chondrules resisted the devitrification this devitrification is necessary for the diffusive communication between chondrule grains and matrix that enables equilibration

timing and climatic impact of greenland interstadials recorded in stalagmites from northern turkey a 50 kyr long exceptionally well dated and highly resolved stalagmite oxygen 18o and carbon 13c isotope record from sofular cave in northwestern turkey helps to further improve the dating of greenland interstadials gi 1 and 3 12 timing of most gi in the sofular record is consistent within 10 to 300 years with the iconic hulu cave record larger divergences 500 years between sofular and hulu are only observed for gi 4 and 7 the sofular record differs from the most recent ngrip chronology by up to several centuries whereas age offsets do not increase systematically with depth the sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern mediterranean to gi whereas a phase lag of 100 years between climate and full ecosystem response is evident finally results of spectral analyses of the sofular isotope records do not support a 1 470 year pacing of gi

the tempo of holocene climatic change in the eastern mediterranean region new high resolution crater lake sediment data from central turkey this study presents results from a multi proxy analysis of cores taken in a crater lake sequence from eski acigol in central turkey which cover the period from pre c 16000 cal yr bp to the present the sediments comprise an upper unit of generally non laminated banded to massive silts and peats of mid to late holocene age overlying a laminated unit of late pleistocene to early mid holocene age the laminae comprising mainly aragonite amorphous silica diatom frustules and organic matter were formed in a relatively deep dilute meromictic lake pollen data indicate an abrupt replacement of artemisia chenopod steppe by grass oak terebinth parkland during the period of laminae deposition marking the start of the holocene a gradual increase in tree pollen during the early holocene came to an end c 6500 cal yr bp u series and adjusted c 14 timescale when mesic deciduous taxa declined at the same time as lake levels fell human impact on regional vegetation is inferred from a sharp decline in oak around 4500 4000 cal yr bp diatom isotopic and mineralogical data indicate that during the second half of the holocene the lake became relatively shallow and oscillated between fresh and brackish evaporated water conditions the contrast between wetter early and drier late holocene climatic conditions is matched by other eastern and central mediterranean proxy climate data while the eski acigol sequence resembles holocene hydroclimatic changes in the saharo arabian zone and was also apparently linked to orbital forcing it is unlikely to have had the same direct cause i e an expansion and subsequent retreat of monsoon rainfall

trace element distributions within ordinary chondrite chondrules implications for chondrule formation conditions and precursors the concentrations of thirty six lithophile elements in the major silicate phases of chondrules have been determined by ion microprobe two types of porphyritic chondrule olivines normal and incompatible rich have been identified the incompatible rich olivines which have forsterite contents that are greater than fo98 appear to have formed under highly reducing conditions the olivine and low ca pyroxene grains in porphyritic chondrules have relatively unfractionated l chondrite normalized ree abundances compared to expectations from equilibrium distribution coefficients this is consistent with porphyritic chondrules having formed at cooling rates of the order of 1000 c h or faster the alkali metal na k rb and cs to al ratios in chondrule glasses vary by two orders of magnitude the lower values possibly being the result of volatile loss from chondrules no correlation was found between alkali metal depletions in chondrule glasses and enrichments in the surrounding rims but any such correlation may have been destroyed by the diffusive redistribution of these elements in rims that is likely to occur even under mild metamorphic conditions the refractory lithophiles with the exception of mg are all highly incompatible in silicate melts and are as a result concentrated in the chondrule glasses the refractory lithophiles in the glass are in most cases unfractionated from one another suggesting that neither vapor phase nor crystal liquid fractionation played a major role in the formation of chondrules or their precursors based largely on the observation that the refractory lithophiles are concentrated in the chondrule glasses it is suggested that previously reported correlations between these elements in bulk chondrule analyses are due to chondrules themselves as opposed to refractory condensates having been their own immediate precursors a simple monte carlo simulation using the compositions of the major chondrule silicate phases reported here supports this hypothesis it is argued that the upper limit of about one observed in the atomic na al ratios of chondule glasses is not due to an albitic precursor but simply reflects that for na to be incorporated into the structure of the melt it must take part in the coupled substitution naalo2 sio2

δd values of n alkanes in tibetan lake sediments and aquatic macrophytes a surface sediment study and application to a 16 ka record from lake koucha abstract a set of lake surface sediment samples and aquatic macrophytes from the eastern and central tibetan plateau and a sediment core from koucha lake northeastern tibetan plateau were analysed for hydrogen isotope signals of aliphatic lipid biomarkers the d values of n alkanes were correlated with those of meteoric water in the summer months and showed increasing pearson correlation coefficients with increasing n alkane chain length r 0 80 for n c 31 while in samples from the most humid regions southeastern tibetan plateau the apparent enrichment factors between meteoric water and lipids are close to those reported for other humid sites e 135 for mid chain and 125 for long chain n alkanes they become smaller e 118 to 41 mean value 86 at sites with a negative moisture balance northeastern and central tibetan plateau and qaidam basin this might be caused by enrichment in deuterium of the source water used for lipid synthesis as a result of lake water evaporation and soil and leaf water evapotranspiration in the core from lake koucha decreasing d values of all n alkanes between 15 and 10 cal ka bp give evidence for an intensification of the asian summer monsoon at ca 9 cal ka bp a ca 15 shift towards higher d values of mid chain n alkanes suggests enhanced evaporation of the lake water which outweighs higher precipitation amounts because of a temperature increase during the early holocene monsoonal maximum only a few surface sediment samples show a significant offset between d values of mid chain n alkanes and n c 31 d mid n c31 and no systematic dependence between this offset and environmental parameters such as mean annual precipitation was found in the core available data for most samples also do not show a significant offset only a slight increase 15 of d mid n c31 at ca 10 0 cal ka bp and a decrease 17 at ca 6 8 cal ka bp might indicate wetter and drier conditions respectively however interpretation of d mid n c31 throughout the record is difficult because of a lack of reliable data for n c 31 in key sections of the core so more records are necessary to further test the potential applicability of d mid n c31 as a proxy for palaeo hydrological conditions

pleistocene water intrusions from the mediterranean and caspian seas into the black sea the hydrological balance of the black sea is governed by riverine input and by the exchange with the mediterranean sea a speleothem record from a cave in northern turkey that tracks the isotopic signature of black sea surface water suggests an open connection to the mediterranean sea in at least twelve periods in the past 670 000 years

variability of the north atlantic oscillation over the past 5 200 years the north atlantic oscillation influences climate in the arctic region and northern europe reconstructions of circulation patterns associated with the north atlantic oscillation from a 5 200 year long lake sediment record suggest that the atmospheric circulation responded to significant transitions in northern hemisphere climate

formation and metamorphism of group a5 chondrules in ordinary chondrites abstract group a5 chondrules have feo rich olivines 4 wt feo and albite normative mesostases and thus are discrete from the major primary chondrule groups group a5 chondrules in six ll chondrites have been studied by cathodoluminescence optical microscopy electron micropobe and in the case of four chondrules removed from semarkona type 3 0 and krymka type 3 1 by instrumental neutron activation analysis olivine and pyroxene compositions vary with petrographic type in a manner resembling group bi chondrules they gain feo and mno lose cao mgo al2o3 and cr2o3 and become more homogeneous but the pyroxene trends are less marked because of lower diffusion rates there are no metamorphically related compositional trends in the mesostasis although compositional zoning is common in the mesostases of two type 3 4 3 7 chondrites group a5 chondrules contain unfractionated lithophile element bulk compositions but as is typical of all chondrules siderophile and chalcophile elements are depleted by about an order of magnitude group a5 chondrules are abundant in equilibrated 100 by number but rare in unequilibrated ordinary chondrites uocs 5 by number but their presence in uocs is not due to the emplacement of metamorphosed chondrules during brecciation because 1 olivine in group a5 chondrules is heterogeneous 2 the olivine displays all the compositional properties of olivine in low petrographic type ordinary chondrites and 3 the mesostasis is not recrystallized the chondrules display trends that are consistent with chondrule to chondrule and chondrule to matrix mineral homogenization and equilibration during metamorphism like the major chondrule groups a1 a2 and b1 in semarkona group a5 is a primary group whose presence provides further insights into chondrule formation process and diversity their bulk composition and redox state suggest that the conditions and temperatures of formation for groups a5 and b1 were similar however their different mesostasis compositions indicate that their post solidification histories were different either group b1 chondruues experienced slower cooling at low temperatures than group a5 during which albite crystallized in the mesostasis group b1 suffered a subsequent mild reheating that caused albite crystallization in the mesostasis or nucleation details for crystallization of albite in the residual melt were different group a1 and a2 chondrules could have been derived from group a5 or b1 like material by reduction and evaporative loss during chondrule formation

the thermoluminescence sensitivity metamorphism relationship in ordinary chondrites experimental data on the mechanism and implications for terrestrial systems hydrothermal annealing experiments have been performed on samples of the sharps meteorite in order to investigate the mechanism responsible for the metamorphism related 105 fold range in the thermoluminescence tl sensitivity in ordinary chondrites duplicate 50 mg samples of meteorite were annealed under the following conditions a 168 h at 785 c and 1 kbar b the same time temperature and pressure but with 2 wt water c 174 h at 855 c and 0 77 kbar with 2 wt water and 2 molal sodium disilicate nadisi d the same time temperature and pressure as the preceding samples but with 10 wt h2o and 2 molal nadisi samples annealed under the first three sets of conditions showed little or no change in their tl sensitivities however the samples annealed with 10 wt water and 2 molal nadisi showed a 3 to 10 fold increase in tl sensitivity and the temperature of the tl peak was suggestive of feldspar in the high temperature form we suggest that these data are consistent with the tl sensitivity metamorphism relationship in ordinary chondrites being due to the formation of the tl phosphor feldspar by the crystallization of chondrule glass

mega chondrules and large igneous textured clasts in julesberg l3 and other ordinary chondrites vapor fractionation shock melting and chondrule formation abstract a petrographic microprobe study of large metal poor igneous textured objects in julesberg l3 and other ordinary chondrites suggests that they can be classified into two petrographic types mega chondrules and large lithic clasts and into two chemical types na poor and na rich mega chondrules show textural evidence of having solidified as freely floating melt droplets whereas lithic clasts formed by the fragmentation of larger objects possibly still larger mega chondrules barred olivine or barred olivine pyroxene textures are most common for mega chondrules whereas a variety of textures occur in large lithic clasts the two petrographic types cannot be distinguished on the basis of modal bulk or phase compositions sodium poor objects are characterized by 1 plagioclase or glass with mainly bytownite composition an70 90 typical 2 subchondritic na al ratios and typically subchondritic volatile element na k and mn abundances and 3 bulk chemical trends that resemble those expected for vapor fractionation processes some na poor objects may have formed by the melting of precursors that formed as condensates or vaporization residues others may have formed by the melting of precursors that formed by fractional condensation or fractional vaporization following vapor fractionation na poor objects or their precursors appear to have reequilibrated at lower temperatures which raised the bulk na content of the objects but not to the levels seen in na rich objects enrichments of fe2 na k and p on the margins of some na poor objects suggest that they partly reacted with volatile rich surroundings both before and after brecciation sodium rich objects are characterized by 1 plagioclase or glass with oligoclase or albite composition an2 25 2 roughly chondritic na al ratios and volatile element na k mn abundances and 3 bulk chemical trends similar to those shown by melt pocket glasses in ordinary chondrites sodium rich melt objects could have formed by the shock melting of chondritic precursors feldspathic compositions for some na rich melt objects can be explained by preferential shock melting of feldspar or feldspathic glass in chondritic target materials literature data imply that the same two chemical populations of objects na poor and na rich occur among smaller normal sized chondrules in type 3 ordinary chondrites suggesting that the same processes that affected large melt objects also affected chondrules

the climate variability in northern levant over the past 20 000 years the levant constitutes an important region for assessing linkages between climate and societal changes throughout the course of human history however large uncertainties remain in our understanding of the region s hydroclimate variability under varying boundary conditions here we present a new high resolution precisely dated speleothem oxygen carbon isotope and sr ca records spanning the last 20 ka from jeita cave northern levant our record reveals a higher lower precipitation evaporation p e balance during the last glacial maximum and bolling interstadial heinrich stadial 1 the early middle holocene is characterized by a trend toward higher p e state culminating between similar to 7 and 6 ka the middle late holocene is characterized by two millennial length drier periods during 5 3 4 2 and 2 8 1 4 ka on submillennial time scale the northern levant climate variability is dominated by 500 year periodicity comparisons with the regional proxy records suggest persistent out of phase climate variability between the northern and southern levant on a wide range of timescales

iron isotopes in chondrules implications for the role of evaporation during chondrule formation we have measured the 57fe of olivines in nine chainpur chondrules all are within error of normal typically 2 1 2 0 most of the chondules could not have lost more than 20 of their feo by rayleigh evaporation and none can have lost more than 61 yet the range of fo contents in these chondrules is fo78 99 9 the isotopic compositions of the chondrules clearly demonstrate that for instance type i chondrules cannot form from type ii chondrules by evaporation of feo under rayleigh conditions the isotopic compositions also place constraints on the minimum cooling rates these chondrules could have experienced these cooling rates must also be equal to or slower than those required to produce the chondrule textures assuming flash heating and evaporation rates like those measured in vacuum the minimum cooling rates necessary to prevent detectable fe isotopic fractionation via rayleigh evaporation approach those needed to produce barred and porphyritic textures the presence of hydrogen in the nebula non linear cooling and other effects will all tend to increase the cooling rates required to prevent 57fe 1 2 0 perhaps by as much as 1 2 orders of magnitude the two most likely ways that the cooling rates required to prevent 57fe 1 2 0 can be kept below those needed to produce barred and porphyritic textures are 1 the ph2 in the nebula was low enough to keep evaporation rates close to those in vacuum or 2 back reaction of chondrules with fe in the gas suppressed isotopic fractionation

compositions and textures of relic forsterite in carbonaceous and unequilibrated ordinary chondrites several percent of the olivine in the c2 c3 and unequilibrated ordinary chondrites uoc can be distinguished by blue cathodoluminescence cl and an unusual composition for forsterite this olivine has the following textural features 1 1 forms cores in single olivine grains 2 2 shows subhedral to euhedral boundaries against rim olivine 3 3 rarely contains inclusions 4 4 has embayments containing olivine like that of the rim 5 5 occurs within chondrules especially in uoc meteorites the blue olivine is always fe poor 0 25 feo 1 0 and shows the following average and maximum values al2o3 0 25 0 5 tio2 0 05 0 09 cao 0 5 0 8 cr2o3 0 15 0 5 and mno 0 02 0 15 vanadium is present within a single olivine and within all blue olivines al ca and ti are strongly positively correlated as are mn fe and cr in olivine surrounding the blue the blue cores are not zoned but each element shows a marked change at the boundary of the blue with al showing the most rapid change these are interpreted as diffusion profiles between rim and core olivine textures suggest initial free growth probably from a gas and later addition of olivine by liquid crystallization to form single crystals or chondrules the unusual olivine composition indicates high temperature growth from a refractory rich reservoir with al entering olivine in tetrahedral coordination vapor growth is suggested as the process allowing the high minor element levels the occurrence of blue olivine in all primitive meteorites indicates that it is relic material which was widespread prior to chondrule and hence meteorite formation similarities in composition exist between this relic olivine and olivine of cosmic dust and deep sea particles pointing to this olivine being a common component in all primitive extraterrestrial material

classification metamorphic history and pre metamorphic composition of chondrules abstract sears et al 1992 and dehart et al 1992 have proposed that the existing scheme for chondrule classification which is based on modal mineralogy texture and mineral composition should be replaced by a new scheme that is based primarily on the compositions of olivine phenocrysts and mesostases but also on their cathodoluminescence we have used published and unpublished compositional data for chondrules in ordinary and carbonaceous chondrites to compare the two classification schemes we find that the new scheme does not preserve the identity of the existing chondrule groups even in the least metamorphosed chondrites because of difficulties in assigning chondrules to the proposed groups and the lack of olivine grains or mesostasis areas of sufficient size 30 of chondrules in some type 3 ordinary chondrites cannot be classified in the new scheme using compositional data for type 4 6 chondrites the existing scheme provides more information about the history of individual chondrules than the new scheme we conclude that textural and modal criteria should be retained for the classification of chondrules

chemical zoning and homogenization of olivines in ordinary chondrites and implications for thermal histories of chondrules we studied the extent and degree of homogenization of chemical zoning of olivines in type 3 ordinary chondrites in order to obtain some constraints on cooling histories of chondrites based on mg fe and cao zoning olivines in type 3 chondrites are classified into four types a single chondrule usually contains olivines with the same type of zoning microporphyritic olivines show all four zoning types barred olivines usually show almost homogenized chemical zoning we have calculated cooling rates or burial depths needed to homogenize the chemical zoning by solving the diffusion equation using the zoning profiles as an initial condition mg fe zoning of olivine may be altered during initial cooling whereas cao zoning is hardly changed barred olivines may be homogenized during initial cooling because their size is relatively small to simulated microporphyritic olivine chondrules cooling from just below the liquidus at moderately high rates is preferable to cooling from above the liquidus at low rates for postaccumulation metamorphism of type 3 chondrites in order to keep mg fe zoning unaltered the maximum metamorphic temperature must be less than about 400 c if we assume cooling rates based on fe ni data calculated cooling rates for both fa and cao homogenization are consistent with those by fe ni data for type 4 chondrites a hot ejecta blanket several tens of meters thick on the surface of a parent body is sufficient to homogenize mg fe zoning if the temperature of the blanket is 600 700 c burial depths for petrologic types of ordinary chondrites in a parent body heated by 26al are broadly consistent with those previously proposed

vegetation fire and climate history of the lesser caucasus a new holocene record from zarishat fen armenia vegetation fire and climate history are investigated in the 10 000 year record of zarishat fen located today in the steppe grasslands of armenia near east pollen based climate quantification provides a reconstruction of seasonal parameters the development of in situ water dependant plants and of forests at lower altitude at 8200 cal a bp echoes the shift from an arid and cold annual precipitation pann 452mm mean temperature of the coldest month mtco 11 1uc early holocene to a more humid and warmer pann 721mm mtco 6 8uc mid late holocene this marks the onset of lower seasonality in particular more effective precipitation brought during late spring by the westerlies paralleling the mediterranean precipitation pattern precipitation in the near east and central asia decreased during the mid late holocene in favour of higher seasonality controlled in winter spring by the siberian high fire history and sedge based fen development record drier phases at approximately 6400 5300 4900 3000 2200 1500 and 400 cal a bp which resemble the precipitation pattern of the south western mediterranean and contrast with the holocene pattern in the south central and south eastern mediterranean regions arid phases in armenia are believed to be related to multi centennial scale variation of westerly activity north atlantic oscillation like copyright 2013 john wiley sons ltd

climatic variability during the last 90 ka of the southern and northern levantine basin as evident from marine records and speleothems abstract the influence of the northern atlantic and tropical monsoonal systems as recorded by the river nile on the climate variability of the southeastern mediterranean was studied in two cores taken by the r v marion dufresne one core taken se of cyprus representing the northern levantine basin core 9501 980 m water depth and the other located 380 km further south represents the southeastern levantine basin in an area influenced by the river nile plume core 9509 884 m water depth the study was performed at relatively high resolution using several proxies 18o of globigerinoides ruber sediment characteristics and index colour parameters in core sections representing the last 86 ka a low resolution alkenone sea surface temperature record was also measured the time frame in both cores was mostly constrained by wiggle matching with the nearby well dated 18o and 13c record of the soreq cave which is mainly influenced by the eastern mediterranean water vapor the sedimentary record of the southern core is strongly influenced by the river nile contribution throughout the last 86 ka as evidenced by the higher sedimentation rates compared with the northern core 20 cm ka vs 5 cm ka continuously darker sediment colour and higher toc values 0 6 0 9 vs 0 25 wt not including sapropels during sapropels s1 and s3 present in both cores the influence of the river nile became more widespread reaching as far as cyprus yet the influence of the river nile remained stronger in the south as evident by the higher toc values in the southern core throughout the entire 90 ka period and the longer duration of s1 in the southern core an anomalous low 18o interval that is not recorded in western mediterranean occurred between 58 and 49 ka in the levantine basin and is more developed in the northern core this period correlates with d o interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle suggesting that the warming mainly impacted the northern levant the eastern mediterranean sea and land area was considerably warmer than the western mediterranean throughout the lgm holocene transition and the 18og ruber drop of 4 5 is significantly greater than the 3 shift found for the western mediterranean 18og bulloides both differences reflecting an increased continental effect from the western to eastern mediterranean comparison between the marine and the land 18o records suggests that the origin of rain over the land is composed of mixed signal from the southern and northern levantine basin the study of 18osea land variations demonstrates that various factors have influenced the sea land relationship during the last 90 ka the amount effect has an important influence on rainfall 18o during interglacial periods particularly sapropel periods whereas during glacial periods increased land distances and elevation differences arising from decrease in sea level may have brought about decrease in 18o of rainfall due to rayleigh distillation processes these influences were superimposed on those of sea surface water 18o changes brought about by continental ice melting and the strong effects felt in the southern levantine basin of the high river nile input during periods of enhanced monsoonal activity

a δ13c and δ2h leaf wax record from the late quaternary loess paleosoil sequence el paraiso central spain abstract the mediterranean peninsula increasingly suffers from droughts and aridity the first consequences of global climate change in that region precise scenarios for the region s future climate predictions require knowledge about the processes of past climate changes but information about the western mediterranean climate and its history is controversial for this study we applied compound specific 13c and 2h analyses on long chain n alkanes in the 8 m el paraiso loess paleosoil sequence lps central spain to investigate climate and environmental changes during the late quaternary the 13c values are most enriched during marine isotope stage mis 3 indicating more arid conditions while lower values during mis 4 and 2 are interpreted to document more humid conditions low values are also recorded for the holocene colluvium which can at least partly be explained with higher concentrations in atmospheric co2 the 2h values are mostly enriched during the last glacial compared to the holocene we suggest that this is mainly controlled by isotopic effects related to the moisture source yet other possible effects like evapotranspirative enrichment and changes in atmospheric circulation patterns shouldn t be ruled out our results corroborate previous findings based on leaf wax patterns geomorphological records and climate models they all indicate relatively humid conditions during mis 2 compared to more arid phases during mis 3

chondrules and other components in c o and e chondrites similarities in their properties and origins we describe three types of chondrules that are common to h3 ll3 cm2 co3 and cv3 chondrites low and high feo porphyritic olivine chondrules contain olivine with fa0 3 8 and fa5 50 respectively and can easily be distinguished petrographically poikilitic pyroxene chondrules have 1 20 vol olivine fa0 2 8 enclosed by low ca pyroxene fs0 5 7 and also occur in e chondrites these three types formed in separate nebular regions which had dimensions and spacings such that a few percent of the chondrules that collided to form compound chondrules were of different types sorting of chondrule precursor material and mixing of chondrule types probably account for most variations in bulk and mineral chemistry among chondrite groups metallic fe ni grains containing 0 1 1 cr si and p are present in low feo olivine chondrules from all type 2 and least metamorphosed type 3 chondrites metal compositions reflect reduction during chondrule formation in the nebula not nebular condensation opaque matrices in type 3 ordinary and carbonaceous chondrites are somewhat similar in composition and mineralogy and probably have related origins we conclude that chondrules in all known chondrite groups share similar nebular origins

properties of chondrules in el3 chondrites comparison with eh3 chondrites and the implications for the formation of enstatite chondrites the study of chondrules provides information about processes occurring in the early solar system in order to ascertain to what extent these processes played a role in determining the properties of the enstatite chondrites the physical and chemical properties of chondrules from three el3 chondrites and three eh3 chondrites have been examined by optical cathodoluminescence cl and electron microprobe techniques properties examined include size texture cl and composition of both individual phases and bulk chondrules the textures distribution of textures and composition of silicates of the el3 chondrules resemble those of eh3 chondrules however the chondrules from the two classes differ in that 1 the size distribution of the el chondrules is skewed to larger values than eh chondrules 2 the enstatite in el chondrules displays varying shades of red cl due to the presence of fine grained sulfides and metal in the silicates and 3 the mesostasis of eh chondrules is enriched in na relative to that of el chondrules the similarities between the chondrules of the two classes suggest similar precursor materials while the differences suggest that there was not a single reservoir of meteoritic chondrules but that their origin was fairly local the differences in the size distribution of chondrules in eh and el chondrites may be explained by aerodynamic and gravitational sorting during accumulation of the meteoric material while differences in cl and mesostasis properties may reflect differences in formation conditions and cooling rate following chondrule formation we argue that our observations are consistent with the formation of enstatite chondrites in a thick dynamic regolith on their parent body

the onset of metamorphism in ordinary and carbonaceous chondrites ordinary and carbonaceous chondrites of the lowest petrologic types were surveyed by xray mapping techniques a variety of metamorphic effects were noted and subjected to detailed analysis using electron microprobe scanning electron microscopy sem transmission electron microscopy tem and cathodoluminescence cl methods the distribution of cr in feo rich olivine systematically changes as metamorphism increases between type 3 0 and type 3 2 igneous zoning patterns are replaced by complex ones and cr rich coatings develop on all grains cr distributions in olivine are controlled by the exsolution of a cr rich phase probably chromite cr in olivine may have been partly present as tetrahedrally coordinated cr3 separation of chromite is nearly complete by petrologic type 3 2 the abundance of chondrules showing an inhomogeneous distribution of alkalis in mesostasis also increases with petrologic type tem shows this to be the result of crystallization of albite residual glass compositions systematically change during metamorphism becoming increasingly rich in k glass in type i chondrules also gains alkalis during metamorphism both types of chondrules were open to an exchange of alkalis with opaque matrix and other chondrules the matrix in the least metamorphosed chondrites is rich in s and na the s is lost from the matrix at the earliest stages of metamorphism due to coalescence of minute grains progressive heating also results in the loss of sulfides from chondrule rims and increases sulfide abundances in coarse matrix assemblages as well as inside chondrules alkalis initially leave the matrix and enter chondrules during early metamorphism feldspar subsequently nucleates in the matrix and na re enters from chondrules these metamorphic trends can be used to refine classification schemes for chondrites cr distributions in olivine are a highly effective tool for assigning petrologic types to the most primitive meteorites and can be used to subdivide types 3 0 and 3 1 into types 3 00 through 3 15 on this basis the most primitive ordinary chondrite known is semarkona although even this meteorite has experienced a small amount of metamorphism allan hills alh a77307 is the least metamorphosed co chondrite and shares many properties with the ungrouped carbonaceous chondrite acfer 094 analytical problems are significant for glasses in type ii chondrules as na is easily lost during microprobe analysis as a result existing schemes for chondrule classification that are based on the alkali content of glasses need to be revised

matrices of type 3 ordinary chondrites primitive nebular records petrologic studies were made on the fine grained matrices of type 3 ordinary chondrites of the lowest petrologic subtype the matrix minerals in order of abundance are olivine fo99 to fo9 enstatite or bronzite augite or subcalcic augite albite fe ni metal troilite magnetite spinel mgal2o4 chromite and calcite fe and mg rich fluffy particles and albite like particles are also major constituents the chemical compositions of olivine and pyroxenes vary within and among the chondrites and are in gross disequilibrium showing that the matrix materials were hardly heated after their formation textural relationships indicate that magnesian olivine was formed after ca pyroxene followed by intermediate to iron rich olivine intermediate olivine was formed from enstatite and metallic iron under relatively oxidizing conditions the observations indicate that matrices of chondrites are neither the fragments of chondrules nor the precursors of chondrules they were mostly the products of condensation and reaction among solids and or between solids and the ambient gas mostly at low temperatures and thus they contain records of primitive processes in the nebula in order to explain the presence of olivines more iron rich than fo50 the presence of free sio2 or a high activity of sio2 in the gas is necessary which was not shown in previous thermochemical calculations mineral assemblages of matrix minerals of chondrites of different chemical groups differ systematically according to oxidation state of the parental meteorites indicating that they were formed at different oxygen fugacities the rims of chondrules and surrounding matrix materials must have accreted onto chondrules during turbulent movements of the nebula

abrupt climate variability since the last deglaciation based on a high resolution multi proxy peat record from nw iran the hand that rocked the cradle of civilization abstract we present a high resolution sub decadal to centennial multi proxy reconstruction of aeolian input and changes in palaeohydrological conditions based on a 13000 yr record from neor lake s peripheral peat in nw iran variations in relative abundances of refractory al zr ti and si redox sensitive fe and mobile k and rb elements total organic carbon toc 13 c toc compound specific leaf wax hydrogen isotopes d carbon accumulation rates and dust fluxes presented here fill a large gap in the existing terrestrial paleoclimate records from the interior of west asia our results suggest that a transition occurred from dry and dusty conditions during the younger dryas yd to a relatively wetter period with higher carbon accumulation rates and low aeolian input during the early holocene 9000 6000 yr bp this period was followed by relatively drier and dustier conditions during middle to late holocene which is consistent with orbital changes in insolation that affected much of the northern hemisphere numerous episodes of high aeolian input spanning a few decades to millennia are prevalent during the middle to late holocene wavelet analysis of variations in ti abundances as a proxy for aeolian input revealed notable periodicities at 230 320 and 470 years with significant periodicities centered around 820 1550 and 3110 years over the last 13000 years comparison with palaeoclimate archives from west asia the north atlantic and african lakes point to a teleconnection between north atlantic climate and the interior of west asia during the last glacial termination and the holocene epoch we further assess the potential role of abrupt climate change on early human societies by comparing our record of palaeoclimate variability with historical geological and archaeological archives from this region the terrestrial record from this study confirms previous evidence from marine sediments of the arabian sea that suggested climate change influenced the termination of the akkadian empire in addition nearly all observed episodes of enhanced dust deposition during the middle to late holocene coincided with times of drought famine and power transitions across the iranian plateau mesopotamia and the eastern mediterranean region these findings indicate that while socio economic factors are traditionally considered to shape ancient human societies in this region the influence of abrupt climate change should not be underestimated

late quaternary record of the vegetation and catchment related changes from lake paravani javakheti south caucasus abstract here we present a palynological and sedimentological record from a 96 cm sediment core covering the last 13 ka aiming to document palaeoecological changes in the central south caucasus driven by climate and or human impact the core was retrieved from lake paravani 2073 m asl 41 27 n 43 48 e located in the steppic grasslands of south caucasus in the samsari javakheti volcanic plateau the geomorphological features observed on the plateau including moraine deposits suggest the presence of local glaciers reaching the lake level during the last glacial periods based on sediment and pollen data three palaeoecological phases have been identified the first phase spanning the younger dryas and the early holocene corresponds to a steppic environment with a limited lake productivity driven by a cold and particularly dry climate according to the age depth model this phase ends near 8500 cal bp with the decline of chenopodiaceae the second phase starts with an important expansion of trees at 8300 cal years bp the delayed afforestation recorded in lake paravani is a pattern that has now been recognised widely through the black sea region s more continental areas as soon as the climatic and edaphic conditions were favourable the main deciduous and coniferous trees expanded concurrently due to the proximity of glacial forest refugia located in western caucasus this second phase marked by a climatic optimum is also characterized by an increase in lake productivity the third phase starts at 2000 3000 cal bp and corresponds to the decline of forests on the plateau and the expansion of herbaceous formations leading to the present day steppic environment this deforestation phase is driven by the deterioration of the climate conditions and human impact

fluvial sediments of the algeti river in southeastern georgia an archive of late quaternary landscape activity and stability in the transcaucasian region abstract in order to obtain information about landscape activity and stability during the late quaternary in the transcaucasian region fluvial sediments of the lower algeti river in se georgia were studied by means of geomorphologic sedimentologic and geochronologic methods these investigations show that sediments aggraded by the late pleistocene braided algeti river were strongly incised around the pleistocene holocene transition and subsequently a small scale pattern of diachronous fluvial terraces deposited by the now meandering river developed in the new valley during the holocene prior to ca 3 cal ka bp active phases of river channel aggradation and overbank sedimentation about 6 cal ka bp and 3 4 3 2 cal ka bp can be linked with climate driven vegetation changes i e stronger fluvial dynamics with sedimentation occurred during more arid and colder periods whereas the caucasian holocene climate optimum between 6 and 3 4 cal ka bp was characterized by stable geomorphologic conditions after 3 cal ka bp strongly increased human impact documented by former pollen studies is reflected by the fluvial dynamics as well i e an activity phase of strong overbank sedimentation 2 7 2 1 cal ka bp occurred during a period when forests in the lesser caucasus were burnt down two subsequent activity phases with fluvial sedimentation can be linked with historic events that probably both influenced vegetation distribution of the region i e a period of flourishing of georgia during the middle age and a time of large scale destruction of the country due to a persian invasion at the end of the 18th century ad respectively thus whereas no influence of tectonic events or fluctuations of the caspian sea level on the fluvial dynamics could be detected se georgia shows its fragile character with respect to climate and human driven vegetation changes similar to other semi arid landscapes of the mediterranean region

δd values of individual n alkanes from terrestrial plants along a climatic gradient implications for the sedimentary biomarker record abstract the compound specific hydrogen isotope composition d of sedimentary n alkanes is increasingly used as a palaeoclimate proxy to explore the origin of the hydrogen isotope signal of n alkanes from higher terrestrial plant biomass in sedimentary organic matter of small lakes we have analysed the n alkane composition and d values of 31 plant biomass samples birch betula beech fagus oak quercus alder alnus hornbeam carpinus and myrtle myrtus as well as non stomata containing sphagnum cladonia and moss from 14 sites along a climatic gradient from northern finland to southern italy eleven of the sites were previously investigated for the n alkane d values in adjacent lake sediments and are compared to the leaf wax n alkane d values the distribution of terrestrial n alkanes in lake sediments was not found to be characteristic of the dominant vegetation around the lake evidently n alkane distributions within the same species at different sites were found to be variable these findings complicate the use of certain n alkane distributions in sediments as a palaeoenvironmental indicator d values of plant biomass n alkanes show a significant positive correlation with the precipitation d values biomass n alkane d values are in general less negative than the associated sedimentary n alkanes of terrestrial origin possibly due to the stronger evapotranspiration during the summer when sampling took place this suggests that n alkanes in leaves show seasonal variations and the sedimentary organic matter receives the lighter isotope signal of the autumn when most leaves are incorporated into the sediment the variability of the d values from non stomata containing plants is much higher than for broadleaf trees since stomata can regulate water loss through evapotranspiration the average chain length acl of n alkanes from deciduous tree leaves increases from north to south with increasing acl the hydrogen isotopic fractionation e between source water and n alkanes also increases our results prove that terrestrial n alkane d values record the d value of precipitation modified by the amount of isotope enrichment in the leaf water due to plant anatomy stomata vs no stomata and site specific meteorological conditions such as evapotranspiration relative humidity and soil moisture therefore terrestrial n alkanes in lake sediments can deliver information on changes in these parameters over geological timescales in lake sediments where aquatic n alkanes such as n c 17 record the lake water d value the isotopic difference between terrestrial and aquatic n alkanes could therefore be used to reconstruct changes in evapotranspiration

retention of sodium during chondrule melting abstract type i chondrules in unequilibrated ordinary and carbonaceous chondrites tend to be enriched in refractory elements and depleted in volatiles relative to bulk ci type ii chondrules show chondritic concentrations of major and minor lithophile elements with na in particular at or slightly above the appropriate bulk rock values element ratio diagrams for chondrule bulk compositions show that type ii chondrules plot on a mixing line between forsterite and a na phase with na al 1 1 whereas type i compositions can be explained by mixing forsterite with melilite or cai or other refractory component with little na calcium in type ii chondrules must have been added as an al free phase such as diopside if their bulk compositions are manipulated subtracting ca as diopside and fe mg as olivine the residue is 90 albite and 10 silica which would be in pyroxene albite was incorporated into the precursors of type ii chondrules which clearly have not been depleted in na although their initial temperatures overlap with those of type i there is no negative correlation between type i liquidus temperatures 1450 1900 c and na al ratios and hence no indication of na loss from the melt if type i precursors contained albite the most aluminous chondrules would have suffered the most extreme na loss but these have the lowest liquidus temperatures their precursors were na depleted whereas those of type ii were na enriched as a function of the abundance of albite the simplest way to obtain the bulk compositions of chondrules is to assemble condensates into precursors at different temperatures and concentration of solids in the nebula or exceptionally rapid heating is required to preserve na in chondrules after melting substantial exchange of na occurred between chondrules and chondrite matrix during parent body metamorphism to petrologic type 3 6

composition and origin of enstatite in e chondrites our petrologic and electron probe study of enstatite in six eh3 4 and 5 chondrites including the previously undescribed allan hills a77156 provides no support for leitch and smith s 1982 model in which crystals and liquids from two chemically distinct partially molten planetesimals are mixed we find that cr and mn concentrations in enstatite grains in matrix and chondrules are not uniquely defined by their cathodoluminescence color wide variations in enstatite compositions among chondrules may partly reflect heterogeneities in the precursor material however correlated variations of cr mn and fe concentrations in enstatite are probably largely due to fractionation during chondrule crystallization the inverse correlation of petrologic type with minor element concentrations in enstatite appears to be a metamorphic effect

petrology and mineralogy of type ii feo rich chondrules in semarkona ll3 0 origin by closed system fractional crystallization with evidence for supercooling abstract the petrology of type ii porphyritic olivine chondrules in semarkona ll3 0 has been studied in detail olivines in these chondrules are euhedral fe richand are strongly zoned from cores to rims of grains in feo fa10 30 cr2o3 0 2 0 6 wt mno 0 2 0 7 wt and cao 0 1 0 4 wt interstitial mesostasis is rich in si aland ca and is glassy with abundant microcrystallites minor minerals include troilite fe ni metaland chromite some olivine grains contain euhedral fayalite rich cores that are probably produced during initial supercooling of the chondrule melt rare relict grains of forsteritic olivine have compositions very similar to olivines in type ia chondrules in semarkona and may result from disaggregation of such chondrules apart from these relics all properties of type ii chondrules can be described by closed system fractional crystallization of droplets which were essentially entirely molten the chondrules did not originate as aggregates of large olivine grains and are unlikely to be fragments of precursor igneous rocks cooling rates of the order of 1000 c h are indicated from peak temperatures of around 1600 c the chondrules show considerable evidence for supercooling and large departures from equilibrium during crystallization there is no evidence for chondrule nebula exchange either during or after crystallization or any secondary processes such as aqueous alteration or thermal metamorphism bulk composition data suggest that precursor material included a refractory ca al ti rich component similar to one of the precursor components of type ia chondrulesand a non refractory fe and si rich component type ia chondrules may have formed from type ii chondrules by loss of fe and volatiles alternatively the two chondrule types may have formed in regions of considerable diversity in the solar nebula from precursor materials with different fe mg ratios

unequilibrated ordinary chondrites a tentative subclassification based on volatile element content for unequilibrated ordinary chondrites uoc two measures of primitiveness are available volatile content in principle reflecting accretion conditions from the solar nebula and metamorphism reflecting reheating in the parent bodies these two measures do not always correlate and we have therefore developed a tentative classification scheme based on volatile content that complements the searset al 1980 scheme based on metamorphism like the latter it subdivides type 3 chondrites on a scale of 3 0 to 3 9 the notation 3 4 0 indicates a meteorite that is subtype 3 4 according to metamorphism and 3 0 according to volatile content the classification is based mainly on c and xe two elements that are little affected by shock induced reheating and to a lesser extent on ar36 bi in and tl of 22 meteorites considered the majority have concordant classifications 0 2 on the two scales however 5 meteorites are richer in volatiles than their metamorphic grade indicates sharps 3 4 0 alha 77011 3 5 0 ngawi 3 6 3 alha 77299 3 7 4 and mezo madaras 3 7 3 it remains to be seen whether these differences indeed denote a more primitive nature some new clues to the formation of chondrites may eventually come from xe and c their concentrations in uoc s vary by more than 5 but the xec ratio remains nearly constant at 3 4 10 3 of the solar system ratio even the ratios for other chondrite classes differ only slightly from that for uoc s e g c3o 1 5 and e3 4 0 4 either the 4 factors determining this ratio t t p and internal surface area of the carbon varied in complementary fashion or more probably they varied only slightly in the entire source region of chondrites

chondrule formation metamorphism brecciation an important new primary chondrule group and the classification of chondrules abstract the recently proposed compositional classification scheme for meteoritic chondrules divides the chondrules into groups depending on the composition of their two major phases olivine or pyroxene and the mesostasis both of which are genetically important the scheme is here applied to discussions of three topics the petrographic classification of roosevelt county 075 the least metamorphosed h chondrite known brecciation an extremely important and ubiquitous process probably experienced by 40 of all unequilibrated ordinary chondrites and the group a5 chondrules in the least metamorphosed ordinary chondrites which have many similarities to chondrules in the highly metamorphosed equilibrated chondrites since composition provides insights into both primary formation properties of the chondrules and the effects of metamorphism on the entire assemblage it is possible to determine the petrographic type of rc075 as 3 1 with unique certainty similarly the new scheme can be applied to individual chondrules without knowledge of the petrographic type of the host chondrite which makes it especially suitable for studying breccias finally the new scheme has revealed the existence of chondrules not identified by previous techniques and which appear to be extremely important like group a1 and a2 chondrules but unlike group b1 chondrules the primitive group a5 chondrules did not supercool during formation but unlike group a1 and a2 chondrules and like group b1 chondrules they did not suffer volatile loss and reduction during formation it is concluded that the compositional classification scheme provides important new insights into the formation and history of chondrules and chondrites which would be overlooked by previous schemes

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

experimental studies of group a1 chondrules abstract dynamic crystallization and annealing experiments have been conducted using a group al chondrule bulk composition to examine the formation and alteration of mesostases that emit a bright yellow cathodoluminescence cl this type of mesostasis has only been observed in group al and a2 chondrules in the least altered chondritic meteorites the dynamic crystallization experiments produce yellow luminescing mesostases only in experiments cooled to their final quench temperatures at the slowest cooling rates the yellow cl is present only where low ca pyroxene grows from the melt so the remaining liquid is enriched in normative anorthite and diopside this composition is strongly associated with yellow luminescence in group al chondrule mesostases low temperature hydrothermal annealing experiments demonstrate that the yellow luminescence can only be destroyed and not enhanced or altered to blue luminescence by aqueous alteration annealing under dry conditions increased both the amount and intensity of the yellow luminescent material annealing experiments designed to further devitrify the mesostasis converted both yellow luminescing and nonluminescent mesostases to blue luminescing mesostases these results confirm that yellow luminescing mesostases are the result of the thermal history group al chondrues experienced prior to accretion and their alteration to blue luminescing mesostases is a direct result of their metamorphic history

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

molecular proxies for paleoclimatology we summarize the applications of molecular proxies in paleoclimatology marine molecular records especially are proving to be of value but certain environmentally persistent compounds can also be measured in lake sediments loess deposits and ice cores the fundamentals of this approach are the molecular parameters the compound abundances and carbon hydrogen nitrogen and oxygen isotopic contents which can be derived by the analysis of sediment extracts these afford proxy measures which can be interpreted in terms of the conditions which control climate and also reflect its operation we discuss two types of proxy those of terrigenous and those of aquatic origin and exemplify their application in the study of marine sediments through the medium of ten case studies based in the atlantic mediterranean and pacific oceans and in antarctica the studies are mainly for periods in the present the holocene and particularly the last glacial interglacial but they also include one study from the cretaceous the terrigenous proxies which are measures of continental vegetation are based on higher plant leaf wax compounds i e long chain circa c30 hydrocarbons alcohols and acids they register the relative contributions of c3 vs c4 type plants to the vegetation in the source areas the two marine proxies are measures of sea surface temperatures sst the longer established one u37k is based on the relative abundances of c37 alkenones photosynthesized by unicellular algae members of the haptophyta the newest proxy tex86 is based on c86 glycerol tetraethers gdgts synthesized in the water column by some of the archaeal microbiota the crenarchaeota

chemical and physical studies of chondrites x cathodoluminescence and phase composition studies of metamorphism and nebular processes in chondrules of type 3 ordinary chondrites abstract the cathodoluminescence cl properties of eight type 3 ordinary chondrites and one l5 chondrite have been determined and phenocryst and mesostasis compositions have been analyzed in the chondrules of four of them semarkona type 3 0 krymka 3 1 allan hills a77214 3 5 and dhajala 3 8 in order to investigate their origins and metamorphic history two major classes of chondrule with eight subdivisions have been identified mainly on the basis of cl properties and 95 of the chondrules can be assigned to these groups on the basis of phenocryst and mesostasis composition class a chondrules consisting of those with plagioclase normative mesostasis with bright cl are subdivided into groups a1 a2 a3 a4 and a5 class b chondrules with little or no cl and having quartz normative mesostases in the least metamorphosed chondrites which becomes feldspathic with metamorphism are subdivided into groups b1 b2 and b3 relationships between the eight chondrule groups can be deduced from their relative abundance in each of the nine chondrites groups a1 a2 b1 and a5 are present in semarkona 15 20 60 5 by number respectively group a5 chondrules in semarkona being more heterogeneous than a5 chondrules in chondrites of higher petrologic type chondrule group a1 evolves into a3 then a4 and then a5 during metamorphism while a2 evolves into a4 and then a5 chondrule group b1 evolves into b2 b3 and then a5 but higher levels of metamorphism are required to complete the series than for the a1 5 series conversion of a group to an adjacent group can be observed in allan hills a77214 3 5 where several chondrules are group b3 in their central regions and group a5 in their outer regions the present chondrule groups are essentially independent of texture since group a and group b chondrules differ in bulk composition redox state and possibly oxygen isotope systematics their relative abundance might be a factor in the creation of the nine chondrite classes

mass independent fractionation of oxygen isotopes in the mesostasis of a chondrule from the semarkona ll3 0 ordinary chondrite abstract a large chondrule from semarkona the most primitive ordinary chondrite known has been discovered to contain a record of mass transport during its formation in most respects it is a normal type i group a1 low feo chondrule that was produced by reduction and mass loss during the unidentified flash heating event that produced the chondrules the most abundant structural component in primitive meteorites we have previously measured elemental abundances and abundance profiles in this chondrule we here report oxygen isotope ratio abundances and ratio abundance profiles we have found that the mesostasis is zoned in oxygen isotope ratio with the center of the chondrule containing isotopically heavier oxygen than the outer regions the outer regions being volatile rich from the diffusion of volatiles into the chondrule during cooling the 17o values range from 2 0 to 9 9 while 18o range from 1 9 to 9 6 more importantly a plot of 17o against 18o has a slope of 1 1 0 2 1 and 0 88 0 10 1 when measured by two independent methods co variation of 17o with 18o that does not follow mass dependent fractionation has often been seen in primitive solar system materials and is usually ascribed to the mixing of different oxygen reservoirs we argue that petrographic and compositional data indicate that this chondrule was completely melted at the time of its formation so that relic grains could not have survived furthermore there is petrographic and compositional evidence that there was no aqueous alteration of this chondrule subsequent to its formation although it is possible to formulate a series of exchanges between the chondrule and external 16o rich and 16o poor reservoirs that may explain the detailed oxygen isotope systematics of this chondrule such a sequence of events looks very contrived we therefore hypothesize that reduction devolatilization and crystallization of the chondrule melt may have produced 16o rich olivines and 16o poor mesostasis plotting on a slope one line as part of the chondrule forming process in an analogous fashion to known chemical mass independent isotopic fractionation mechanisms during cooling volatiles and oxygen near the terrestrial line in oxygen isotope composition produced the outer zone of volatile rich and 16o rich mesostasis the chondrule therefore not only retains a record of considerable mass transport accompanying formation but also may indicate that the isotopes of oxygen underwent mass independent fractionation during the process

geometry of the pamir hindu kush intermediate depth earthquake zone from local seismic data 1 we present new seismicity images based on a two year seismic deployment in the pamir and sw tien shan a total of 9532 earthquakes were detected located and rigorously assessed in a multistage automatic procedure utilizing state of the art picking algorithms waveform cross correlation and multi event relocation the obtained catalog provides new information on crustal seismicity and reveals the geometry and internal structure of the pamir hindu kush intermediate depth seismic zone with improved detail and resolution the relocated seismicity clearly defines at least two distinct planes one beneath the pamir and the other beneath the hindu kush separated by a gap across which strike and dip directions change abruptly the pamir seismic zone forms a thin approximately 10 km width curviplanar arc that strikes east west and dips south at its eastern end and then progressively turns by 90 to reach a north south strike and a due eastward dip at its southwestern termination pamir deep seismicity outlines several streaks at depths between 70 and 240 km with the deepest events occurring at its southwestern end intermediate depth earthquakes are clearly separated from shallow crustal seismicity which is confined to the uppermost 20 25 km the hindu kush seismic zone extends from 40 to 250 km depth and generally strikes east west yet bends northeast toward the pamir at its eastern end it may be divided vertically into upper and lower parts separated by a gap at approximately 150 km depth in the upper part events form a plane that is 15 25 km thick in cross section and dips sub vertically north to northwest seismic activity is more virile in the lower part where several distinct clusters form a complex pattern of sub parallel planes the observed geometry could be reconciled either with a model of two sided subduction of eurasian and previously underthrusted indian continental lithosphere or by a purely eurasian origin of both pamir and hindu kush seismic zones which necessitates a contortion and oversteepening of the latter

base level changes river avulsions and holocene human settlement dynamics in the caspian sea area middle kura valley south caucasus abstract geomorphological geochronological and geoarchaeological analysis focusing on six tributaries of the kura river provide valuable data concerning sedimentation rhythmicity and holocene human settlement distribution at a regional scale seven new radiocarbon dates from the upstream part of these hydrosystems complemented the existing radiocarbon dataset n 32 obtained downstream these data seem to indicate that upstream hydrosystems also reacted to marine regressions by powerful riverbed incisions and to transgression phases by thick valley infillings from at least as early as the upper pleistocene the retroactive morphogenic effects were also perceived in intra mountainous areas far from the caspian shoreline the land use patterns of the caucasian societies dwelling in the valley of the kura hydrosystem were affected by temporary river avulsions resulting in silty fans over the high terraces during the neolithic chalcolithic periods these river avulsions seem to be governed by local climate and base level changes linked to fluctuations of the caspian sea level over time this is spatially and diachronically evidenced in settlement distribution with almost exclusive localization on perched silty fans and river runoff from the key period of neolithic development in the region these new data must be considered in future geoarchaeological analyses concerning the caspian sea basin and will contribute to the enhancement of the relative caspian sea level curve for the past 40 ka

the semarkona meteorite first recorded occurrence of smectite in an ordinary chondrite and its implications abstract semarkona is an unshocked unequilibrated ordinary chondrite much of the interchondrule matrix and the mesostases of some chondrules and clasts have been hydrothermally altered analyses of altered materials and opaque matrix are presented ca and fe have been redistributed from primary anhydrous phases into calcite and na fe smectite respectively in semarkona the process possibly requires open system behavior inconsistent with the conventional view of metamorphism of the ordinary chondrites the low petrologic type previously assigned to semarkona is the result of retrograde metamorphism under aqueous conditions of a higher temperature mineral assemblage semarkona and possibly bishunpur should be assigned to petrologic type 2

fe mn systematics of type iia chondrules in unequilibrated co cr and ordinary chondrites we have examined fe mn systematics of 34 type iia chondrules in eight highly unequilibrated co cr and ordinary chondrites using new data from this study and prior studies from our laboratory olivine grains from type iia chondrules in co chondrites and unequilibrated ordinary chondrites uoc have significantly different fe mn ratios with mean molar fe mn 99 and 44 respectively olivine analyses from both these chondrite groups show well defined trends in mn versus fe afu and molar fe mn versus fe mg diagrams in general type iia chondrules in cr chondrites have properties intermediate between those in uoc and co chondrites in most uoc and cr type iia chondrules the fe mn ratio of olivine decreases during crystallization whereas in co chondrites the fe mn ratio does not appear to change it is difficult to interpret the observed fe mn trends in terms of differing moderately volatile element depletions inherited from precursor materials instead we suggest that significant differences in the abundances of silicates and sulfides metals in the precursor material as well as open system behavior during chondrule formation were responsible for establishing the different fe mn trends using fe mn mg systematics we are able to identify relict grains in type iia chondrules which could be derived from previous generations of chondrules including chondrules from other chondrite groups and possibly chondritic reservoirs that have not been sampled previously