borehole imagery of meteoric and marine ice layers in the amery ice shelf east antarctica a real time video camera probe was deployed in a hot water drilled borehole through the amery ice shelf east antarctica where a total ice thickness of 480 m included at least 200 m of basal marine ice down looking and side looking digital video footage showed a striking transition from white bubbly meteoric ice above to dark marine ice below but the transition was neither microscopically sharp nor flat indicating the uneven nature at centimetre scale of the ice shelf base upstream where the marine ice first started to accrete marine ice features were imaged including platelet structures cell inclusions entrained particles and the interface with sea water at the base the cells are assumed to be entrained sea water and were present throughout the lower 100 150m of the marine ice column becoming larger and more prevalent as the lower surface was approached until near the base they became channels large enough that the camera field of view could not contain them platelets in the marine ice at depth appeared to be as large as 1 2 cm in diameter particles were visible in the borehole meltwater probably marine and mineral particles liberated by the drill but their distribution varied with depth

rapid disintegration of the wordie ice shelf in response to atmospheric warming the breaking up of ice shelves around the antarctic peninsula has been cited1 as a sign that a dangerous warming is beginning in antarctica here we present satellite images showing the disintegration of the wordie ice shelf which lies off the west coast of the antarctic peninsula fig 1 fracture either in the form of surface crevasses or rifts extending to the bottom of the ice shelf has been responsible for iceberg calving and weakening the central region of the ice shelf these fracture processes which led to retreat of the ice front were apparently enhanced by the presence of increased amounts of melt water resulting from a warming trend recorded in mean annual air temperatures in marguerite bay if this warming trend continues other nearby ice shelves on the antarctic peninsula may be at risk but substantial additional warming would be required before similar processes could initiate breakup of the ross and filchner ronne ice shelves which help stabilize the west antarctic ice sheet

central european vegetation response to abrupt climate change at 8 2 ka oxygen isotope records show a major climatic reversal at 8 2 ka in greenland and europe annually laminated sediments from two lakes in switzerland and germany were sampled contiguously to assess the response of european vegetation to climate change ca 8 2 ka with time resolution and precision comparable to those of the greenland ice cores the pollen assemblages show pronounced and immediate responses 0 20 yr of terrestrial vegetation to the climatic change at 8 2 ka a sudden collapse of corylus avellana hazel was accompanied by the rapid expansion of pinus pine betula birch and tilia linden and by the invasion of fagus silvatica beech and abies alba fir vegetational changes suggest that climatic cooling reduced drought stress allowing more drought sensitive and taller growing species to out compete corylus avellana by forming denser forest canopies climate cooling at 8 2 ka and the immediate reorganization of terrestrial ecosystems has gone unrecognized by previous pollen studies on the basis of our data we conclude that the early holocene high abundance of c avellana in europe was climatically caused and we question the conventional opinion that postglacial expansions of f silvatica and a alba were controlled by low migration rates rather than by climate the close connection between climatic change and vegetational response at a subcontinental scale implies that forecasted global warming may trigger rapid collapses expansions and invasions of tree species

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

basal melting at the ekstrom ice shelf antarctica estimated from mass flux divergence we characterize the basal mass balance of the ekstr om ice shelf dronning maud land antarctica using interferometrically derived surface velocities and ice thickness measurements from radio echo sounding res the surface velocities are based on data from european remote sensing satellites 1 and 2 ers 1 2 during 1994 97 the ice thickness grid consists of 136 res profiles acquired between 1996 and 2006 mass fluxes are calculated along selected res profiles where possible to reduce uncertainties from ice thickness interpolation elsewhere large scale mass fluxes are calculated using interpolated ice thickness data themass flux into the ekstr om ice shelf from themain grounded drainage basins is estimated to be 3 19 0 4gt a 1 the mass flux near the ice shelf front is 2 67 0 3gt a 1 assuming steady state and based on the equation of continuity we interpret the residual mass flux as a combined effect of snow accumulation and subglacial melting refreezing using net snow accumulation rates from previous studies we link the mass flux divergence in irregular shaped polygons to processes beneath the ice shelf the highest subglacial melt rates of 1 1ma 1 are found near the grounding zone of two main inflow glaciers and around the german station neumayer iii the detection of unlikely refreezing in a small area 15 km west of neumayer iii is attributed to both dataset inaccuracies and a possibly past violation of the steady state assumption in general the method and input data allow mapping of the spatial distribution of basal melting and the results are in good agreement with several previous studies

argon 40 argon 39 age spectra of apollo 17 highlands breccia samples by laser step heating and the age of the serenitatis basin we have obtained high resolution 21 63 steps 40ar 39ar age spectra using a continuous laser system on 19 submilligram samples of melt rocks and clasts from apollo 17 samples collected from the pre imbrian highlands in the easternmost part of the serenitatis basin the samples include poikilitic melt rocks inferred to have been formed in the serenitatis basin forming impact aphanitic melt rock whose compositions vary and whose provenance is uncertain and granulite gabbro and melt clasts three of the poikilitic melts have similar age spectrum plateau ages 72395 96 3893 16 ma 2 72535 7 3887 16 ma 76315 150 3900 16 ma with a weighted mean age of 3893 9 ma which we interpret as the best age for the serenitatis basin forming impact published 40ar 39ar age spectrum ages of apollo 17 poikilitic melts are consistent with our new age but are much less precise two poikilitic melts did not give plateaus and the maxima in their age spectra indicate ages of 3869 ma 72558 7 and 3743 ma 77135 178 plateau ages of two poikilitic melts and two gabbro clasts from 73155 range from 3854 16 ma to 3937 16 ma and have probably been affected by the ubiquitous older clasts and by post formation heating impact events plateau ages from two of the aphanitic melt blobs and two granulites in sample 72255 fall in the narrow range of 3850 16 ma to 3869 16 ma with a weighted mean of 3862 8 ma two of the aphanitic melt blobs from 72255 have ages of 3883 16 ma and 3894 ma whereas a poikilitic melt clast of different composition from the serenitatis melts has an age of 3835 16 ma which is the upper limit for the accretion of 72255 these data suggest that either the aphanitic melts vary in age as is also suggested by their varying chemical compositions or they formed in the 72255 accretionary event about 3 84 3 85 ga and older relict material is responsible for the dispersion of ages in any case the aphanitic melts do not appear to be serenitatis products our age for the serenitatis impact shows on the basis of the isotopic age evidence alone that serenitatis is 20 25 ma and probably 55 60 ma older than imbrium 3870 ma and probably 3836 ma dalrymple and ryder 1993 noritic granulite sample 78527 has a plateau age of 4146 17 ma representing a minimum age for cooling of this sample in the early lunar crust so far there is no convincing evidence in the lunar melt rock record for basin forming impacts significantly older than 3 9 ga

rock cities and ruiniform relief forms processes terminology abstract spectacular rock cut landscapes consisting of closely spaced residual rock blocks separated by narrow intersecting corridors are variously termed as rock cities and ruiniform relief the former term has apparently never been formally defined except in the local czech literature whereas the latter was applied in various contexts making the terminology confusing this paper provides a global overview of forms processes and controls behind such rock city ruiniform landscapes and develops geomorphological terminology for such rock cut landscapes including the proposal that rock city becomes a legitimate scientific term rock cities and ruiniform relief are two different types of rock erosional morphology typified by the presence of a street pattern in the former and highly weathered surfaces of rock residuals in the latter although there is some overlap between the two examples of rock cities or ruiniform relief may be found in different lithologies and in a wide range of climates from hyper arid to humid classic localities include northern czechia and adjacent parts of poland and germany australia central sahara and the gran sabana in venezuela lithologies particularly suitable to the development of this type of erosional morphology include mainly sandstones followed by limestones dolomites conglomerates tuffs but igneous rocks such as granites or rhyolites are also known to support this type of relief the combination of sufficient rock strength to support steep rock faces and the presence of discontinuities which preferentially eroded turn to streets and squares in the rock cities appears as the basic prerequisite a wide range of processes are involved in their formation including surface and subsurface weathering mass movements salt tectonics karst processes in both carbonate and silicate rocks piping fluvial erosion and aeolian abrasion despite being spectacular landscapes very few models of long term evolution of rock city and ruiniform relief have been presented in the literature and it is unlikely that any one scenario would apply to all situations rather rock cities are examples of geomorphological convergence

lunar meteorites from oman abstract sixty named lunar meteorite stones representing about 24 falls have been found in oman in an area of 10 7 103 km2 in southern oman lunar meteorite areal densities average 1 g km 2 all lunar meteorites from oman are breccias although two are dominated by large igneous clasts a mare basalt and a crystalline impact melt breccia among the meteorites the range of compositions is large 9 32 al2o3 2 5 21 1 feo 0 3 38 g g 1 sm and 1 to 22 5 ng g 1 ir the proportion of nonmare lunar meteorites is higher among those from oman than those from antarctica or africa omani lunar meteorites extend the compositional range of lunar rocks as known from the apollo collection and from lunar meteorites from other continents some of the feldspathic meteorites are highly magnesian high mgo mgo feo compared with most similarly feldspathic apollo rocks two have greater concentrations of incompatible trace elements than all but a few apollo samples a few have moderately high abundances of siderophile elements from impacts of iron meteorites on the moon all lunar meteorites from oman are contaminated to various degrees with terrestrial na k p zn as se br sr sb ba u carbonates or sulfates the contamination is not so great however that it seriously compromises the scientific usefulness of the meteorites as samples from randomly distributed locations on the moon

on the relative and absolute ages of seven lunar front face basins ii from the crater counts abstract from counts of postbasin craters larger than 30 km in diameter lying within or near to seven giant front face lunar basins relative ages for the basins may be obtained these relative ages correlate well with absolute basin ages found from viscosity arguments in r b baldwin 1987 icarus 70 from crater counts the basins are in the following sequence of increasing relative age orientale imbrium crisium serenitatis nectaris humorum and the unnamed basin lying between werner and the altai ring the absolute ages from baldwin 1987 range from 3 80 to 4 30 109 years while a correlation with the relative ages of this paper yields a range of 3 79 to 4 27 109 years the discrepancy is largely due to serenitatis where the debris from imbrium has presumably buried some post serenitatis craters from both sets of data there is no evidence that a terminal lunar cataclysm ever occured

high resolution measurements of absolute thorium abundances on the lunar surface the lunar prospector lp gamma ray spectrometer grs has been used to map the global abundance of thorium on the lunar surface a global map of absolute thorium abundances on a 2 by 2 equal area pixel scale is presented using new detector modeling results and low altitude lp data because thorium is relatively abundant in kreep rich material these data provide fundamental information regarding the locations and importance of terranes that are rich in kreep bearing materials

feldspathic lunar meteorites pecora escarpment 02007 and dhofar 489 contamination of the surface of the lunar highlands by post basin impacts abstract pca pecora escarpment 02007 and dhofar 489 are both meteorites from the feldspathic highlands of the moon pca 02007 is a feldspathic breccia consisting of lithified regolith from the lunar surface it has concentrations of both incompatible and siderophile elements that are at the high end of the ranges for feldspathic lunar meteorites dhofar 489 is a feldspathic breccia composed mainly of impact melted material from an unknown depth beneath the regolith concentrations of incompatible and siderophile elements are the lowest among brecciated lunar meteorites among 19 known feldspathic lunar meteorites all of which presumably originate from random locations in the highlands concentrations of incompatible elements like sm and th tend to increase with those of siderophile elements like ir feldspathic meteorites with high concentrations of both suites of elements are usually regolith breccias iridium derives mainly from micrometeorites that accumulate in the regolith with duration of surface exposure micrometeorites have low concentrations of incompatible elements however so the correlation must reflect a three component system we postulate that the correlation between sm and ir occurs because the surface of the feldspathic highlands terrane has become increasingly contaminated with time in sm rich material from the procellarum kreep terrane that has been redistributed across the lunar surface by impacts of moderate sized post basin impacts the most sm rich regolith breccias among feldspathic lunar meteorites are about 3 enriched compared to the most sm poor breccias but this level of enrichment requires only a few percent sm rich material typical of the procellarum kreep terrane the meteorite data suggest that nowhere in the feldspathic highlands are the concentrations of k rare earths and th measured by the lunar prospector mission at the surface representative of the underlying bedrock all surfaces covered by old regolith as opposed to fresh ejecta are at least slightly contaminated dhofar 489 is one of 15 paired lunar meteorite stones from oman total mass of meteorite 1037 g on the basis of its unusually high mg fe ratio the meteorite is likely to have originated from northern feldspathic highlands

understanding the lunar surface and space moon interactions the surface of the moon is a critical boundary that shapes our understanding of the moon as a whole all geologic mapping and remote sensing techniques utilize only the outermost portion of the moon before leaving the moon for study in our laboratories all lunar samples that have been studied existed at or very near the surface with the exception of the deeply probing geophysical techniques our understanding of the interior of the moon is derived from surficial but not superficial information coupled with boundary of the lunar crust it is the lower boundary layer of the tenuous lunar atmosphere and constitutes both a source and a sink for atmospheric gases the surface is also where the moon interacts with the space environment causing changes in the physical nature of lunar materials and provides a laboratory for the study of processes that occur on all airless bodies the data obtained remotely by the galileo clementine and lunar prospector missions as well as data derived from lunar meteorites have resulted in major changes to our understanding of global distributions of chemistry and rocks this chapter summarizes the current understanding of this critical interface the surface of the moon in its role as the lower boundary of the lunar atmosphere the upper boundary of the crust and the window through which we view through remote sensing the composition of the crust and the history of the moon in this post lunar prospector time the view of the moon has changed lending new perspectives to lunar samples and lunar processes but the new view will likely remain in flux as we continue to digest the results from these recent space missions and move forward to a new era of lunar exploration despite the freshness of our perspective this is an important moment to capture

apollo 12 breccia 12013 impact induced partial pb loss in zircon and its implications for lunar geochronology abstract apollo 12 breccia 12013 is composed of two portions one grey in colour the other black the grey portion of the breccia consists mainly of felsite thought to have formed during a single crystallisation event while the black part is characterized by presence of lithic fragments of noritic rocks and individual plagioclase crystals in this study u pb analyses of ca phosphate and zircon grains were conducted in both portions of the breccia the zircon grains within the grey portion yielded a large range of ages 4154 7 to 4308 6 ma 2 and show decreasing u and th concentrations within the younger grains moreover some grains exhibit recrystallisation features and potentially formation of neoblasts the latter process requires high temperatures above 1600 1700 c leading to the decomposition of the primary zircon grain and subsequent formation of new zircon occurring as neoblasts as a result of the high temperatures the u pb system of the remaining original zircon grains was most likely open for pb diffusion causing partial resetting and the observed range of 207pb 206pb ages the event that led to the pb loss in zircon could potentially be dated by the u pb system in ca phosphates which have a weighted average 207pb 206pb age across both lithologies of 3924 3 ma 95 conf this age is identical within error to the combined average 207pb 206pb age of 3926 2 ma that was previously obtained from ca phosphates within apollo 14 breccias zircon grains in apollo 12 impact melt breccias and the lunar meteorite sau 169 this age was interpreted to date the imbrium impact the zircon grains located within the black portion of the breccia yielded a similar range of ages 4123 13 to 4328 14 ma 2 to those in the grey portion given the brecciated nature of this part of the sample the interpretation of these ages as representing igneous crystallisation or resetting by impact events remains ambiguous since there is no direct link to their source rocks via textural relationships or crystal chemistry similarly the currently available zircon data set for all lunar samples may be distorted by partial pb loss resulting in meaningless and misleading age distribution patterns therefore it is crucial to fully understand and recognize the processes and conditions that may lead to partial resetting of the u pb system in zircon in order to better constrain the magmatic and impact history of the moon

unusual vegetation stability in a lowland pine forest area doksy region czech republic although the holocene is characterized by prominent vegetation changes some vegetation types can reveal surprising stability we studied holocene woodland history in a sandstone pseudokarst area

a rb sr and sm nd isotope geochronology and trace element study of lunar meteorite lapaz icefield 02205 abstract rubidium strontium and samarium neodymium isotopes of lunar meteorite lapaz icefield lap 02205 are consistent with derivation of the parent magma from a source region similar to that which produced the apollo 12 low ti olivine basalts followed by mixing of the magma with small amounts 1 2 wt of trace element enriched material similar to lunar kreep rich sample sau 169 the crystallization age of lap 02205 is most precisely dated by an internal rb sr isochron of 2991 14 ma with an initial 87sr 88sr at the time of crystallization of 0 699836 0 000010 leachable ree rich phosphate phases of lap 02205 do not plot on a sm nd mineral isochron indicating contamination or open system behavior of the phosphates excluding anomalous phases from the calculation of a sm nd isochron yields a crystallization age of 2992 85 initial e143nd 2 9 0 8 that is within error of the rb sr age and in agreement with other independent age determinations for lap 02205 from ar ar and u pb methods the calculated 147sm 144nd source ratios for lap 02205 various apollo 12 and 15 basalts and samples with strong affinities to kreep sau 169 nwa 773 15386 are uncorrelated with their crystallization ages this finding does not support the involvement of a common kreep component as a heat source for lunar melting events that occurred after crystallization of the lunar magma ocean

environment and landscape management during the middle neolithic in southern france evidence for agro sylvo pastoral systems in the middle rhone valley abstract rescue excavations in the middle rhone valley have provided opportunities to develop innovative strategies for the study of palaeoenvironments these strategies involve sampling and analysis of botanical remains recovered not only from archaeological sites but also in off site pedosedimentary sequences thought to be poor in botanical remains thus these remains phytoliths pedo charcoal give access to unexplored depositional contexts such as alluvial plains moreover off site data are useful because they minimise the hazard of cultural bias e g selection of species during wood gathering comparison of data collected in the alluvial plain with data obtained via anthracological analyses of karstic caves and rock shelters in the hinterland suggests a complex agro sylvo pastoral management of the landscape during the middle neolithic we propose a pattern that supposes considerable specialization in use of plains vs slopes in the landscape and a strong and continuous human pressure on the vegetation and soils between 4500 and 3500 cal bc nevertheless these constraints are not sufficient to explain the persistence of such a system for more than a millennium favourable climatic conditions are thought to have been a determining factor in the persistence of an ecologically meta stable relationship between human societies and their natural environment

ocean circulation beneath the ronne ice shelf the intimate thermal contact between the base of antarctic ice shelves and the underlying ocean enables changes in climate to have a rapid impact on the outflow of ice from the interior of antarctica1 2 furthermore water modified by passage under ice shelves particularly in the weddell sea is believed to be an important constituent of antarctic bottom water3 a water mass that can be observed as far north as 50 n in the deep oceans4 antarctic bottom water is both cold and oxygen rich and plays an important part in the cooling and ventilation of the world s oceans because of the difficulty in gaining access the oceano graphic regime beneath ice shelves is very poorly sampled5 by successfully drilling through the ice however we were able to obtain oceanographic data from beneath the largest antarctic ice shelf the ronne filchner ice shelf in the southern weddell sea we find that our data agree well with the predictions of a relatively simple oceanographic plume model of sub ice shelf circulation6 this model can therefore be used with some confidence to investigate the links between climate changes ice shelf melting and bottom water production

phosphate ages in apollo 14 breccias resolving multiple impact events with high precision u pb sims analyses abstract the u pb systems of apatite and merrillite grains within four separate apollo 14 impact melt breccia samples were analysed by secondary ion mass spectrometry no systematic difference was identified between the 207 pb 206 pb ages of the apatites and merrillites a combined 207 pb 206 pb age of 3927 2 ma 95 conf is determined for three of these samples 14305 103 3926 4 ma 14306 150 3926 6 ma 14314 13 3929 4 ma by combining these data with the ages previously obtained for zircons in apollo 12 impact melt breccia fragments and the lunar meteorite sau 169 a weighted average age of 3926 2 ma 95 conf is obtained which is attributed to the formation of the imbrium basin an age of 3943 5 ma is determined for the fourth breccia 14321 134 which is similar to ages of 3946 15 ma and 3958 19 ma obtained from several older phosphates in 14305 103 and 14314 13 the weighted average of these three older ages is 3944 4 ma 95 conf this is indistinguishable to the age 3938 4 ma 2 obtained for a different apollo 14 impact melt breccia in a previous study after investigating likely sources for this older 3940 ma age we conclude that the humorum or serenitatis basin forming events are likely candidates the potential identification of two large impact events within 15 myrs has important implications for the rate of lunar bombardment around 3 95 3 92 ga this study demonstrates the importance of high precision age determinations for interpreting the impact record of the moon as documented in lunar samples

petrogenesis and chronology of lunar meteorite northwest africa 4472 a kreepy regolith breccia from the moon northwest africa nwa 4472 is a polymict lunar regolith meteorite the sample is kreep rich high concentrations of potassium rare earth elements and phosphorus and comprises a heterogeneous array of lithic and mineral fragments these clasts and mineral fragments were sourced from a range of lunar rock types including the lunar high magnesian suite the high alkali suite kreep basalts mare basalts and a variety of impact crater environments the kreep rich nature of nwa 4472 indicates that the sample was ejected from regolith on the nearside of the moon in the procellarum kreep terrane and we have used lunar prospector gamma ray remote sensing data to show that the meteorite is most similar to and most likely sourced from regoliths adjacent to the imbrium impact basin u pb and pb pb age dates of nwa 4472 phosphate phases reveal that the breccia has sampled pre nectarian 4 35 ga rocks related to early episodes of kreep driven magmatism some younger phosphate u pb and pb pb age dates are likely indicative of impact resetting events at 3 9 4 ga consistent with the suggested timing of basin formation on the moon our study also shows that nwa 4472 has sampled impact melts and glass with an alkali depleted incompatible trace element rich high sc low rb th ratios low k compositional signature not related to typical apollo high k kreep or that sampled by kreepy lunar meteorite sayh al uhaymir sau 169 this provides evidence that there are numerous sources of kreep rich protoliths on the moon

support for the lunar cataclysm hypothesis from lunar meteorite impact melt ages lunar meteorites represent a more random sampling of lunar material than the apollo or luna collections and as such lunar meteorite impact melt ages are the most important data in nearly 30 years with which to reexamine the lunar cataclysm hypothesis within the lunar meteorite breccias mac 88105 que 93069 dag 262 and dag 400 seven to nine different impact events are represented with 40ar 39ar ages between 2 76 and 3 92 billion years ago ga the lack of impact melt older than 3 92 ga supports the concept of a short intense period of bombardment in the earth moon system at approximately 3 9 ga this was an anomalous spike of impact activity on the otherwise declining impact frequency curve

geochemistry and petrology of howardite miller range 11100 a lithologically diverse piece of the vestan regolith the howardite eucrite diogenite hed clan of meteorites which most likely originate from the asteroid vesta provide an opportunity to combine in depth sample analysis with the comprehensive remote sensing data set from nasa s recent dawn mission miller range mil 11100 an antarctic howardite contains diverse rock and mineral fragments from common hed lithologies diogenites cumulate eucrites and basaltic eucrites it also contains a rare pyroxferroite bearing lithology not recognized in hed until recently and rare mg rich fo86 91 olivine crystals that possibly represent material excavated from the vestan mantle clast components underwent different histories of thermal and impact metamorphism before being incorporated into this sample reflecting the diversity in geological histories experienced by different parts of vesta the bulk chemical composition and petrography of mil 11100 suggest that it is akin to the fragmental howardite meteorites the strong lithological heterogeneity across this sample suggests that at least some parts of the vestan regolith show heterogeneity on the mm scale we combine the outcomes of this study with data from nasa s dawn mission and hypothesize on possible source regions for this meteorite on the surface of vesta

lunar and martian meteorite delivery services launch mechanisms for lunar and martian meteorites have been investigated by integrating physical modeling constraints geochemical cosmic ray exposure cre constraints and petrologic constraints the potential source region for lunar meteorites is remarkably small compared to the final crater volume cre constraints indicate that most launches start at depths of 3 2 m and cratering theory implies derivation of suitably accelerated objects from a subvolume with diameter only about 0 3 the final crater diameter the shallow depth provenance is probably related to shock wave interference enhanced by the lunar regolith s extremely low compressional wave velocity cre constraints alone imply that four to five separate launch events are represented among the eight well studied lunar meteorites most of the lunar meteorites are regolith breccias which tend to show only limited compositional diversity within any kilometer scale region of the moon several others are polymict breccias which also show relatively subdued compositional diversity compared to igneous rocks the observed diversity among these samples in terms of abundances of mare basalt and kreep and in mg mg fe ratio implies that among eight well studied lunar meteorites only two potential source crater pairings are plausible between asuka 881757 y 793169 most probable and between y 793274 eet875721 altogether these eight lunar meteorites apparently represent at least six separate source craters including three in the past 105 years and five in the past 106 years cre constraints imply that snc meteorites are launched from systematically greater depths than lunar meteorites sncs are also systematically bigger and all nine well studied sncs are uncommonly young by martian standards mafic igneous rocks comparison between viking and apollo results reveals that rocks the size of common meteorites are remarkably scarce in the martian regolith probably due to pervasive weathering a plausible explanation for these trends is that most old small and shallow rocks on mars have been weakened by a two stage process of brecciation followed by pervasive weathering to the point where they seldom survive the stresses of spallation off the planet the scarcity of source crater pairing among the lunar meteorites implies that these objects can be launched from craters much smaller than previously estimated and tends to support the suggestion of rabinowitz 1993 astrophys j 407 412 427 that present day cratering rates for the earth moon region may be higher than previously estimated

a unique chunk of the moon in the late 1970s after the apollo lunar missions researchers and collectors began finding meteorites in deserts that turned out to be rocks ejected from the moon s surface some time in the past in his perspective korotev 1 discusses results reported in the same issue by gnos et al 2 on a unique lunar meteorite collected in january 2002 this object designated sayh al uhaymir 169 has unusually high concentrations of thorium and related elements much higher than those of other lunar meteorites or all but a few samples returned during the apollo missions on the basis of lead isotope dating sayh al uhaymir 169 also appears to be older than thorium rich apollo samples calling into question past age assignments for the imbrium basin impact 1 http www sciencemag org cgi content full 305 5684 622 2 http www sciencemag org cgi content short 305 5684 657

present day soil distribution explained by prehistoric land use podzol arenosol variation in an ancient woodland in denmark abstract archaeological evidence has rarely been used by soil scientists to explain the distribution of present day soils yet recent human influence is known to be important for all soils sites with abandoned prehistoric fields are commonly found throughout western europe but the impact on present day soils is not fully known the studied site alstrup krat is an intact bronze and iron age site with a well preserved system of fields infields and common areas common it was abandoned around 2000 bp and has been beech wood since this paper concerns the connection between the present day soil distribution and this former land use the methods used in the field were soil survey intensive ditching and profile descriptions and these were combined with soil physical and chemical laboratory analyses texture oc n p fe al optical density on oxalate extracts odoe and base ions this revealed two distinct soil types whose borders coincided with the prehistoric common infield border on the dominant parent material sandy and gravelly tills hyperdystric arenosols are found in the infields and haplic podzols in the common area entic podzols or spodic arenosols are developed in the common infield transition zone and in infields that were furthest from the dwellings during cultivation podzols had been expected in the infields as iron age agriculture is believed to have exhausted the soil and caused podzolization chemical and physical differences between infields and the common area did not explain the observed soil distribution the only difference between the two adjacent areas was prehistoric land use until 2000 years ago the main factor is probably agriculture during the iron age which physically rejuvenated the soil in the infields archaeological information thus provided a powerful tool for explaining soil spatial distribution where standard soil science variables and methods would have failed

new lunar meteorites impact melt and regolith breccias and large scale heterogeneities of the upper lunar crust we have analyzed nine highland lunar meteorites lunaites using mainly inaa several of these rocks are difficult to classify dhofar 081 is basically a fragmental breccia but much of its groundmass features a glassy fluidized texture that is indicative of localized shock melting also much of the matrix glass is swirly brown suggesting a possible regolith derivation we interpret dar al gani dag 400 as an extremely immature regolith breccia consisting mainly of impact melt breccia clasts we interpret dhofar 026 as an unusually complex anorthositic impact melt breccia with scattered ovoid globules that formed as clasts of mafic subophitic impact melt the presence of mafic crystalline globules in a lunar material even one so clearly impact heated suggests that it may have originated as a regolith our new data and a synthesis of literature data suggest a contrast in al2o3 incompatible element systematics between impact melts from the central nearside highlands where apollo sampling occurred and those from the general highland surface of the moon impact melts from the general highland surface tend to have systematically lower incompatible element concentration at any given al2o3 concentration than those from apollo 16 in the case of dhofar 026 both the bulk rock and a comparatively al poor composition 14 wt al2o3 7 g g sm extrapolated for the globules manifest incompatible element contents well below the apollo 16 trend impact melts from luna 20 57e distribute more along the general highland trend than along the apollo 16 trend siderophile elements also show a distinctive composition for apollo 16 impact melts ni ir averaging 1 8x chondritic in contrast lunaite impact melt breccias have consistently chondritic ni ir impact melts from luna 20 and other apollo sites show average ni ir almost as high as those from apollo 16 the prevalence of this distinctive ni ir ratio at such widely separated nearside sites suggests that debris from one extraordinarily large impact may dominate the megaregolith siderophile component of a nearside region 2300 km or more across highland polymict breccia lunaites and other kreep poor highland regolith samples manifest a strong anticorrelation between al2o3 and mg the magnesian component probably represents the chemical signature of the mg suite of pristine nonmare rocks in its most pure form unaltered by the major kreep assimilation that is so common among apollo mg suite samples the average composition of the ferroan anorthositic component is now well constrained at al2o3 29 30 wt implying about 17 19 wt modal mafic silicates in good agreement with the composition predicted for flotation crust over a ferroan magma ocean warren 1990

common asteroid break up events of eucrites diogenites and howardites and cosmic ray production rates for noble gases in achondrites we determined the cosmic ray produced noble gas abundances in eight diogenites four eucrites and four howardites using these and additional noble gas and chemical data from the literature composition and shielding dependent production rates of achondrites for 3he 21ne 38ar 78kr 83kr and126xe were derived based on 81krkr exposure ages the cosmogenic ratio 22ne 21ne is found to be a valid shielding indicator for all howardites eucrites and diogenites heds this ratio correlates with other shielding dependent ratios such as 78kr 83kr 80kr 83kr 124xe 131xe 126xe 131xe and 128xe 131xe we show that strong correlations for these ratios also exist for basaltic lunar rocks the new production rates were used for the calculation of exposure ages for all heds with known noble gas abundances two major exposure age clusters at 21 ma and 38 ma are observed in all three classes we find that five asteroid break up events characterized by exposure ages 6 1 ma 12 2 ma 21 4 ma 38 8 ma and 73 3 ma produced all diogenites fifteen out of seventeen howardites and twenty eight out of thirty nine eucrites we conclude that asteroidal or cometary impact events at such times on one or several parent bodies are responsible for the ejection of eucrites howardites and diogenites probable parent bodies are multiple 4 vesta derived kilometer sized objects of basaltic achondritic composition reaching the 3 1 resonance region a proposed source area for meteorites the direct ejection from vesta and capture by earth of basaltic meteorites has been shown to be dynamically difficult in such a scenario large events 38 ma and 21 ma ago are required liberating simultaneously material representing vesta s surface eucrites howardites and interior regions diogenites

melting of ice shelves and the mass balance of antarctica we calculate the present ice budget for antarctica from measurements of accumulation minus iceberg calving run off and in situ melting beneath the floating ice shelves the resulting negative mass balance of 469 gt year 1 differs substantially from other recent estimates but some components are subject to high temporal variability and budget uncertainties of 20 50 annual accumulation from an earlier review is adjusted to include the antarctic peninsula for a total of 2144 gt year 1 an iceberg production rate of 2016 gt year 1 is obtained from the volume of large icebergs calculated from satellite images since 1978 and from the results of an international iceberg census project ice shelf melting of 544 gt year 1 is derived from physical and geochemical observations of meltwater outflow glaciological field studies and modeling of the sub ice ocean circulation the highest melt rates occur near ice fronts and deep within sub ice cavities run off from the ice sheet surface and from beneath the grounded ice is taken to be 53 gt year 1 less than half of the negative mass balance need come from the grounded ice to account for the unattributed 0 45 mm year 1 in the ipcc best estimate of the recent global sea level rise

the contribution of the sensitive high resolution ion microprobe shrimp to lunar geochronology abstract the sensitive high resolution ion microprobe shrimp developed at the australian national university anu was the first of the high resolution ion microprobes the impact of this instrument on geochronological research over the last twenty years has been immense this is particularly so for lunar geochronology where it has opened up avenues of research that were not possible using conventional tims techniques the great advantage of shrimp is that it provides a means for determining precise u pb isotopic ratios on selected micron size areas on polished grains of zircon and other u bearing minerals one of the first projects undertaken on the newly invented shrimp i was an investigation of u pb ages of lunar zircon using shrimp multiple analyses could be made on areas of individual zircons to test the stability of u pb systems in shocked grains also by analysing grains in situ textural relationships between the analysed zircon and the components of the sample breccia could be used in the interpretation of the shrimp data as a result of this research it was realised that most lunar zircons have ages up to 500 ma older than the imbrium and serenitatis impacts at ca 3 9 ga demonstrating that the zircons have not been affected by the these impact events although heating and shock effects have profoundly disturbed other dating systems this has opened the way for research into the early lunar magmatic and bombardment record for example recent shrimp results have revealed profound differences in the ages of zircons from breccias from the apollo 14 and apollo 17 sample sites raising new questions about the evolution of lunar magmatism also multiple shrimp analyses on complex lunar zircons have shown that these grains can record u pb disturbance by later impact events shrimp u pb age determinations on phosphates in lunar meteorites has identified lunar events not recognised in samples from the apollo program shrimp based research on lunar materials is ongoing and in combination with other chemical and structural evidence continues to stimulate new ideas on the early evolution of the moon

human induced changes in fire regime and subsequent alteration of the sandstone landscape of northern bohemia czech republic multiproxy palaeoecological evidence from a sandstone region in northern czech republic was collected to explore the impact of fire disturbances on the decline of the broadleaved forests during the late bronze age 3250 3050 cal bp it has been hypothesized that human accelerated soil leaching affected the nutrient availability in the sandstone area thus promoting the expansion of oligotrophic adapted plant communities in the late holocene little is known about the mechanisms which induced such large scale vegetation transformation we sought to determine which driving forces were involved using independent proxy records soil and sedimentary charcoal pollen and fungal spores local fire history was derived from the variation in charcoal accumulation rates char preserved in eustach peatbog the fire frequency ff estimation over the past 7500 years revealed distinct phases of increased burning between 3100 and 2120 cal bp 3 0 fires 1000 yr 1 and 1400 600 cal bp 4 3 fires 1000 yr 1 rapid c

revisiting the field geology of taurus littrow abstract integration of apollo 17 field observations and photographs sample investigations lunar reconnaissance orbiter camera images chandrayaan 1 moon mineralogy mapper m3 spectra and miniature radio frequency mini rf s band radar images provides new insights into the geology of the valley of taurus littrow on the moon connecting the various remote observations to sample data enables a set of new conclusions to be drawn regarding the geological evolution of the valley structural considerations and published and recalculated 40ar 39ar analyses of samples from the north massif and the sculptured hills indicate that the crisium basin formed about 3 93 ga the serenitatis basin about 3 82 ga and the imbrium basin no earlier than 3 82 ga and no later than the average of 3 72 ga for 33 age dates from samples of the valley s mare basalts strong evidence continues to support the conclusion of others lucchitta 1972 spudis et al 2011 fassett et al 2012 that the sculptured hills physiographic unit consists of imbrium ejecta interpretation of m3 spectral data and apollo 17 samples indicate that rock units of the sculptured hills consist of a largely coherent mg suite pluton lroc nac stereo images and mini rf data indicate the presence of several exposed pyroclastic fissures across the sculptured hills rim boulders at camelot crater constitute nearly in situ wall rocks of that crater rather than ejecta and provide an opportunity for investigations of remanent magnetic field orientation at the time of the eruption of late mare basalt lavas in the valley paleomagnetic field orientation information also may be obtained relative to melt breccia contacts in north massif boulders that suggest original horizontal orientations lroc images indicate the existence of two temporally separate light mantle avalanche deposits the origin potential flow mechanisms and geology of the youngest avalanche from the south massif have been clarified the existence of two distinct light mantle avalanches raises doubt about the association of either light mantle avalanche with secondary impacts related to the tycho impact event alternatively the lee lincoln thrust fault appears to have triggered the second light mantle avalanche between 70 and 110 ma a simple structural analysis shows that this thrust fault dips 20 25 to the southwest where it crosses the north massif and to the west where it crosses the valley floor mini rf data reveal a line of reduced reflections roughly perpendicular to contours on the north massif about 3 km to the east of the lee lincoln fault although this line is possibly an older ancillary fault lroc nac stereo images indicate that it may be best explained as a pyroclastic fissure a debris flow of dark apparent pyroclastic ash lies below the southeast end of the potential fissure finally young lunar impact glass sample 70019 has been precisely located within lroc nac images and oriented for the first time using 60 mm f l sample documentation photographs sample 70019 can now be employed in lunar paleomagnetic field orientation studies

holocene forest transformations in sandstone landscapes of the czech republic stand scale comparison of charcoal and pollen records stand scale palaeoecology in sandstone landscapes provides insight into contrasting holocene forest succession trajectories sharp geomorphological gradients in this investigated area which in add

ice shelf basal melting at the grounding line measured from seismic observations analysis of seismic data provides a new technique to measure basal melting of an ice shelf close to the grounding line internal reflections have been observed within the ice on a seismic reflection profile at the grounding line of ronne ice shelf the changes in ice thickness above and below these reflections have been used in a steady state model to calculate the basal mass flux of the ice shelf soon after the ice begins to float strain rates within the ice calculated during the modeling agree with values from nearby survey data the calculated melt rates range between 0 and 7 m yr 1 with an estimated standard error of 2 4 m yr 1 in reasonable agreement with earlier estimates based on surface glaciological observations limitations in the method include the difficulties in determining reflector geometry from a single seismic section and also the limitations imposed by the assumption of steady state additional seismic data would greatly reduce these limitations

petrography mineralogy and geochemistry of lunar meteorite sayh al uhaymir 300 we report here the petrography mineralogy and geochemistry of lunar meteorite sayh al uhaymir 300 sau 300 sau 300 is dominated by it fine grained crystalline matrix surrounding mineral fragments plagioclase pyroxene olivine and ilmenite and lithic clasts mainly feldspathic to noritic mare basalt and kreepy rocks are absent glass melt veins and impact melts are present indicating that the rock has been subjected to a second impact event feni metal and troilite grains were observed in the matrix major element concentrations of sau 300 al 2 o 3 21 6 wt and feo s 16 wt are very similar to those of two basalt bearing feldspathic rei regolith breccias calcalong creek and yamato y 983885 however the rare earth element ree abundances and pattern of sau 300 resemble the patterns of feldspathic highlands meteorites e g queen alexandra range que 93069 and dar al gani dag 400 and the average lunar highlands crust it has a relatively lree enriched 7 to 10 x ci pattern with a positive eu anomaly similar to 11 x ci values of fe mn ratios of olivine pyroxene and the bulk sample are essentially consistent with l lunar origin sau 300 also contains high siderophile abundances with a chondritic ni ir ratio sau 300 has experienced moderate terrestrial weathering as its bulk sr concentration is elevated compared to other lunar meteorites and apollo and luna samples mineral chemistry and trace clement abundances of sau 300 fall within the ranges of lunar feldspathic meteorites and fan rocks sau 300 is a feldspathic impact melt breccia predominantly composed of feldspathic highlands rocks with a small amount of mafic component with a bulk mg of 0 67 it is the most mafic of the feldspathic meteorites and represents a lunar surface composition distinct from any other known lunar meteorites oil the basis of its low th concentration 0 46 ppm and its lack of kreepy and mare basaltic components the source region of sau 300 could have been within a highland terrain a great distance from the imbrium impact basin probably on the far side of the moon

h and cl isotope systematics of apatite in brecciated lunar meteorites northwest africa 4472 northwest africa 773 sayh al uhaymir 169 and kalahari 009 we have investigated the h and cl systematics in apatite from four brecciated lunar meteorites in northwest africa nwa 4472 most of the apatites contain 2000 6000 ppm h2o with d between 200 and 0 except for one grain isolated in the matrix which contains 6000 ppm h2o with d of 500 900 this low d apatite contains 2500 7500 ppm cl associated with 37cl of 15 20 while the high d grain contains 2500 ppm cl with 37cl of 7 15 in nwa 773 apatites in a first group contain 700 2500 ppm h2o with d values averaging around 0 100 while apatites in a second group contain 5500 16500 ppm h2o with d 250 50 in sayh al uhaymir sau 169 and kalahari kal 009 apatites are similar in terms of their h2o contents 600 3000 ppm and d values 100 to 200 in sau 169 apatites contain 6000 10 000 ppm cl characterized by 37cl of 5 12 overall most of the analyzed apatite grains have d within the range reported for carbonaceous chondrites similar to apatite analyzed in ancient 3 9 ga lunar magmatic one grain in nwa 4472 has h and cl isotope compositions similar to apatite from mare basalts with an age of 4 35 ga this grain could be a representative of the oldest known lunar volcanic activity finally since numerous evolved clasts in nwa 773 formed through silicate liquid immiscibility the apatite grains with extremely high h2o contents reaching pure hydroxylapatite composition could provide insights into the effects of such process on the evolution of volatiles in lunar magmas

first access to the ocean beneath ekstromisen antarctica by means of hot water drilling a hot water drill developed during the past 2 years at alfred wegener institute was used to penetrate the ekstrom ice shelf several times near the georg von neumayer station the drilling operation was successful and the initial large diameter 35 cm allowed easy access to the ocean one hole was used to install an ultrasonic echo sounder which recorded the ablation at the ice shelf bottom continuously another hole was used for emplacement of a thermistor string throughout the 237 m thick ice shelf for ice temperature measurements several ctd profiles in the 175 m deepwater column and the analysis of water samples provided valuable data for the understanding of ice shelf ocean interactions

constraining the source regions of lunar meteorites using orbital geochemical data lunar meteorites provide important new samples of the moon remote from regions visited by the apollo and luna sample return missions petrologic and geochemical analysis of these meteorites combined with orbital remote sensing measurements have enabled additional discoveries about the composition and age of the lunar surface on a global scale however the interpretation of these samples is limited by the fact that we do not know the source region of any individual lunar meteorite here we investigate the link between meteorite and source region on the moon using the lunar prospector gamma ray spectrometer remote sensing data set for the elements fe ti and th the approach has been validated using apollo and luna bulk regolith samples and we have applied it to 48 meteorites excluding paired stones our approach is able broadly to differentiate the best compositional matches as potential regions of origin for the various classes of lunar meteorites basaltic and intermediate fe regolith breccia meteorites are found to have the best constrained potential launch sites with some impact breccias and pristine mare basalts also having reasonably well defined potential source regions launch areas for highland feldspathic meteorites are much less well constrained and the addition of another element such as mg will probably be required to identify potential source regions for these

pb pb geochronology petrography and chemistry of zr rich accessory minerals zirconolite tranquillityite and baddeleyite in mare basalt 10047 abstract in situ u pb isotopic measurements were carried out by ion microprobe on the zr rich accessory minerals zirconolite cazrti2o7 tranquillityite fe82 zry 2ti3si3o24 and baddeleyite zro2 in low k high ti mare basalt 10047 collected during the apollo 11 mission the analysed minerals are concentrated in pockets of late stage mesostasis that comprises an intergrowth of silica barian k feldspar and si al k glass from a phaneritic subophitic basalt comprising mainly pyroxene plagioclase ilmenite cristobalite and troilite most zr rich minerals are unaltered however some tranquillityite is replaced by a complex intergrowth of zirconolite baddeleyite ilmenite and fayalite suggesting that the mineral became unstable during crystallization several baddeleyite crystals have also undergone alteration to secondary zircon zirconolite was analysed in thin section 10047 11 and tranquillityite and baddeleyite in 10047 227 using a 6 m primary ion beam both zirconolite and tranquillityite have significant u and low initial pb contents and are highly suitable for pb pb dating fifteen analyses of zirconolite give a 207pb 206pb age of 3708 7 ma 207pb 206pb 204pb 206pb isochron 95 confidence including renormalisation of ratios and twenty five analyses of tranquillityite give 3710 6 ma the 207pb 206pb dates are consistent with each other and refine results from an earlier study baddeleyite data were less precise mainly due to lower secondary ionisation efficiency our results show that zirconolite and tranquillityite can provide precise isotopic dates and given their presence in other samples they represent important u pb chronometers for refining lunar geology

characterization of multiple lithologies within the lunar feldspathic regolith breccia meteorite northeast africa 001 lunar meteorite northeast africa nea 001 is a feldspathic regolith breccia this study presents the results of electron microprobe and la icp ms analyses of a section of nea 001 we identify a range of lunar lithologies including feldspathic impact melt ferroan noritic anorthosite and magnesian feldspathic clasts and several very low titanium vlt basalt clasts the largest of these basalt clasts has a rare earth element ree pattern with light ree lree depletion and a positive euanomaly this clast also exhibits low incompatible trace element ite concentrations e g 0 1 ppm th 0 5 ppm sm indicating that it has originated from a parent melt that did not assimilate kreep material positive eu anomalies and such low ite concentrations are uncharacteristic of most basalts returned by the apollo and luna missions and basaltic lunar meteorite samples we suggest that these features are consistent with the vlt clasts crystallizing from a parent melt which was derived from early mantle cumulates that formed prior to the separation of plagioclase in the lunar magma ocean as has previously been proposed for some other lunar vlt basalts feldspathic impact melts within the sample are found to be more mafic than estimations for the composition of the upper feldspathic lunar crust suggesting that they may have melted and incorporated material from the lower lunar crust possibly in large basin forming events the generally feldspathic nature of the impact melt clasts lack of a kreep component and the compositions of the basaltic clasts leads us to suggest that the meteorite has been sourced from the outer feldspathic highlands terrane fht o probably on the lunar farside and within about 1000 km of sources of both low ti and vlt basalts the latter possibly existing as cryptomaria deposits

thermohaline circulation and interaction between ice shelf cavities and the adjacent open ocean the circulation system in an ice shelf cavity is driven by buoyancy fluxes due to melting and freezing of ice and horizontal pressure gradients at the interface between the cavity and the open ocean hence the inflow and outflow pattern and the hydrography in the open ocean influence the general hydrographic condition in the cavity which at least provides the potential for melting and freezing processes applying a three dimensional ocean general circulation model to an idealized ice shelf cavity geometry coupled with an open ocean at a topographic ice shelf barrier we found an important parameter controlling the interaction between these two systems idealized studies for different ice shelf and sea bottom topographies and forcing mechanisms for the open ocean show that the ice shelf edge represents a natural barrier for barotropic interaction because of the sudden decrease in water column thickness since the water column thickness and the coriolis force determine the characteristics for geostrophic flow separated circulation systems arise for the open ocean and the ice shelf cavity only in areas where constant water column thickness and from the oceanographic point of view constant f h contours can be observed across the barrier an increased barotropic current can surmount the ice edge and ventilate the water mass beneath the ice shelf this is only the case at lateral sloping sidewalls or at deep depressions which can be found for example in the southern weddell sea in all other cases the circulation in the ice shelf cavity is closed and almost unaffected by the hydrography outside the barrier

the procellarum kreep terrane implications for mare volcanism and lunar evolution geophysical remote sensing and sample data demonstrate that the procellarum and imbrium regions of the moon make up a unique geochemical crustal province here dubbed the procellarum kreep terrane geochemical studies of imbrium s ejecta and the crustal structure of the imbrium and serenitatis basins both suggest that a large portion of the lunar crust in this locale is composed of a material similar in composition to apollo 15 kreep basalt kreep basalt has about 300 times more uranium and thorium than chondrites so this implies that a large portion of moon s heat producing elements is located within this single crustal province the spatial distribution of mare volcanism closely parallels the confines of the procellarum kreep terrane and this suggests a causal relationship between the two phenomena we have modeled the moon s thermal evolution using a simple thermal conduction model and show that as a result of the high abundance of heat producing elements that are found in the procellarum kreep terrane partial melting of the underlying mantle is an inevitable outcome specifically by placing a 10 km kreep basalt layer at the base of the crust there our model predicts that mare volcanism should span most of the moon s history and that the depth of melting should increase with time to a maximum depth of about 600 km we suggest that the 500 km seismic discontinuity that is observed in the apollo seismic data may represent this maximum depth of melting our model also predicts that the kreep basalt layer should remain partially molten for a few billion years thus the imbrium impact event most likely excavated into a partially molten kreep basalt magma chamber we postulate that the kreep basalt composition is a by product of mixing urkreep with shallow partial melts of the underlying mantle since mg suite rocks are likely derived from crystallizing kreep basalt the provenance of these plutonic rocks is likely to be unique to this region of the moon

pinpointing the source of a lunar meteorite implications for the evolution of the moon the lunar meteorite sayh al uhaymir 169 consists of an impact melt breccia extremely enriched with potassium rare earth elements and phosphorus thorium 32 7 parts per million ppm uranium 8 6 ppm potassium oxide 0 54 weight percent and adherent regolith the isotope systematics of the meteorite record four lunar impact events at 3909 13 million years ago ma 2800 ma 200 ma and 0 34 ma and collision with earth sometime after 9 7 1 3 thousand years ago with these data we can link the impact melt breccia to imbrium and pinpoint the source region of the meteorite to the lalande impact crater

drilling to the beds of the greenland and antarctic ice sheets a review we give a review of drilling to the beds of the greenland and antarctic ice sheets with a history of just a century we use a chronological rather than a geographical ordering to emphasize the way drilling has developed the review is divided into two parts core drilling and hole only drilling for access to the beds or the deep interior of the ice sheets this is an overview not a comprehensive report on each project while we have endeavoured to include all projects that fit our selection criteria we have not provided all the technical details

anthracology and taphonomy from wood gathering to charcoal analysis a review of the taphonomic processes modifying charcoal assemblages in archaeological contexts abstract a discussion on the representativeness of charcoal from archaeological contexts and their potential for palaeoecological reconstruction is presented the charcoal deposits studied are the result of human activities and natural processes difficult to separate on the basis of their effects only this is why taphonomy should not be limited to the study of charcoal after the extinction of fire as a result our questioning has been widened to include the entire succession of processes from past vegetation to the anthracological diagram we propose a review of the taphonomic processes affecting anthracological assemblages in archaeological contexts from wood gathering to the analysis of charcoal results human practices appear clearly as the first filter determining or conditioning the assemblage the combustion process can induce a double filter by limiting the taxonomic information and by falsifying the initial quantity of burned wood post depositional agents represent a third level of filters between the vegetation and the anthracological assemblage finally sampling and quantification methods can also induce a distortion of the assemblage the aim of this paper is to present the state of the discipline today the problems already solved and the questions that remain to be studied

formal subdivision of the holocene series epoch a discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommission on quaternary stratigraphy international commission on stratigraphy this discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommision on quaternary stratigraphy sqs of the international commission on stratigraphy ics considers the prospects for a formal subdivision of the holocene series epoch although previous attempts to subdivide the holocene have proved inconclusive recent developments in quaternary stratigraphy notably the definition of the pleistocene holocene boundary and the emergence of formal subdivisions of the pleistocene series epoch mean that it may be timely to revisit this matter the quaternary literature reveals a widespread but variable informal usage of a tripartite division of the holocene early middle or mid and late and we argue that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology we propose an early middle holocene boundary at 8200 a bp and a middle late holocene boundary at 4200 a bp each of which is linked to a global stratotype section and point gssp should the proposal find a broad measure of support from the quaternary community a submission will be made to the international union of geological sciences iugs via the sqs and the ics for formal ratification of this subdivision of the holocene series epoch copyright 2012 john wiley sons ltd

impact history of the apollo 17 landing site revealed by u pb sims ages secondary ion mass spectrometry sims u pb ages of ca phosphates from four texturally distinct breccia samples 72255 76055 76015 76215 collected at the apollo 17 landing site were obtained in

comparative petrology geochemistry and petrogenesis of evolved low ti lunar mare basalt meteorites from the lapaz icefield antarctica new data is presented for five evolved low ti lunar mare basalt meteorites from the lapaz icefield antarctica lap 02205 lap 02224 lap 02226 lap 02436 and lap 03632 these basalts have nearly identical mineralogies textures and geochemical compositions and are therefore considered to be paired the lapaz basalts contain olivine fo64 2 and pyroxene fs32wo8en60 to fs84 86 wo15en2 0 crystals that record extreme chemical fractionation to fe enrichment at the rims and evidence for silicate liquid immiscibility and incompatible element enrichment in the mesostasis the basalts also contain feni metals with unusually high co and ni contents similar to some apollo 12 basalts and a single phase network of melt veins and fusion crusts the fusion crust has similar chemical characteristics to the whole rock for the lapaz basalts whereas the melt veins represent localized melting of the basalt and have an endogenous origin the crystallization conditions and evolved nature of the lapaz basalts are consistent with fractionation of olivine and chromite from a parental liquid similar in composition to some olivine phyric apollo 12 and apollo 15 basalts or lunar low ti pyroclastic glasses however the young reported ages for the lapaz mare basalts 2 9 ga and their relative incompatible element enrichment compared to apollo mare basalts and pyroclastic glasses indicate they cannot be directly related instead the lapaz mare basalts may represent fractionated melts from a magmatic system fed by similar degrees of partial melting of a mantle source similar to that of the low ti apollo mare basalts or pyroclastic glasses but which possessed greater incompatible element enrichment despite textural differences the lapaz basalts and mare basalt meteorite nwa 032 have similar ages and compositions and may originate from the same magmatic system on the moon

ice ocean interaction on ronne ice shelf antarctica detailed glaciological studies have been completed at 28 sites lying on an approximate flow line extending 760 km across ronne ice shelf parameters measured at each location include ice velocity thickness principal strain rates surface elevation temperature and accumulation rate the data have been used in a steady state model to derive the basal mass flux and the temperature profile with depth at each site from the principles of mass and energy conservation these calculations indicate basal melting in excess of 1 m yr 1 over the first 100 km of the flow line downstream of the grounding line where the ice shelf is between 1200 m and 1600 m thick the maximum melt rates in this region occur near the inland margin and exceed 4 m yr 1 melting continues at a lesser rate over the next 200 km before freezing commences freezing then dominates up to the final 100 km before the ice front resulting in the accumulation of a layer of basal sea ice up to 50 m thick this is rapidly removed as melt rates increase to over 6 m yr 1 at the ice front the cumulative effect of this pattern of basal accumulation and ablation is the wastage by melting of 85 of the mass discharged across the grounding line before it reaches the ice front supporting evidence for a layer of saline ice underlying the ice shelf is provided by the strength of basal radar reflections observed during radio echo sounding of ice thickness in the region where mass balance calculations suggest an accretion of basal sea ice reflection coefficients are consistently low ranging from 6 db to 38 db most of these weak reflections are believed to originate from the true base of the ice shelf the additional energy loss being the result of increased attenuation of the radar signal within the saline layer the derived pattern of basal melting and freezing is consistent with a simple model of sub ice shelf oceanic circulation involving a deep thermohaline convection cell dense saline water which is formed over the continental shelf during winter when the sea surface freezes drains into the deepest parts of the sub ice shelf cavity at the inland margin where this water mass comes into contact with the ice shelf its temperature is 1 c above the local pressure freezing point melting of ice results producing a buoyant outflow of cold relatively fresh water along the ice shelf base basal freezing occurs towards the ice front where the ascending water becomes supercooled this circulation has important implications for the production of antarctic bottom water and for the response of the ice shelf to driving stresses through the temperature dependent viscosity of ice

a charcoal record of holocene woodland succession from sandstone rock shelters of north bohemia czech republic archaeological excavations at north bohemian sandstone rock shelters have uncovered complex evidence of intermittent human presence since the late palaeolithic to recent times in this paper we investigate the history of holocene woodlands based on charcoal assemblages from stratified sandy accumulations under archaeologically investigated rock shelters in total we carried out anthracological analyses of eight profiles excavated under rock shelters our study shows that the number of charcoal taxa correlated with local environmental diversity around the rock shelters charcoals of pinus sylvestris were abundant in all the profiles analysed profiles in bottom parts of valleys recorded a higher abundance of broadleaf tree charcoal the abundance of oak gradually decreased from the bronze age onwards as oak got replaced by pine and locally beech fir and spruce today several of the recorded woody species are rare or even absent in the sandstone region under study we focused on comparing anthracological results with results of pollen analyses carried out in the same areas our results demonstrate that when results from different types of archives are compared it is possible to gain a more differentiated insight into local vegetation composition this may carry wide methodological implications

effects of logging and fire on runoff and erosion on highly erodible granitic soils in tasmania a set of rainfall simulator experiments was carried out in a logged forest in tasmania australia to quantify the impact of logging and fire on runoff and soil loss a large portable rainfall simulator was developed for the experiments to help overcome problems associated with spatially varying hydraulic and erosion properties of the soil simulated rainfall events with intensities of approximately 35 75 and 150 mm h 1 were applied to four 300 m2 plots with different levels of surface disturbance severely burnt logged and burnt with high mechanical disturbance logged with low mechanical disturbance and undisturbed the experiments indicated that the amount of runoff and soil loss from the plots depended on the type and degree of disturbance to the natural biotic crust developed on this soil erodibility per unit runoff was greatest on the severely burnt plot but runoff on the mechanically disturbed site was so great that it produced the highest total sediment yield on an event basis runoff production was similar on the three plots where the natural biotic crust was largely intact and was low relative to the plot with high mechanical disturbance total sediment yield was typically higher on logged plots than on unlogged plots

mechanisms of fast flow in jakobshavns isbrae west greenland part i measurements of temperature and water level in deep boreholes several holes were drilled to depths of 1500 1630 m along a profile across jakobshavns isbrae 50 km upstream from the calving front drilling was by hot water and required approximately 20 h the holes were rapidly closed by refreezing but it was possible to instrument them with thermistors and tilt sensors before this occurred near the margins of the ice stream the holes reached the bed and connected with the subglacial drainage system water level changes recorded in these holes are discussed in terms of the basal hydraulic system the temperature measurements show that the glacier is temperate based moreover extrapolation of a measured temperature profile and its curvature suggests that a temperate layer of substantial thickness may exist at the bed near the center of the ice stream there is a striking difference in the shapes of temperature profiles measured at different locations beneath the center line the temperature minimum is at a considerably smaller relative depth than near the margins but it is nearly the same in magnitude 22 1 c this may indicate a disproportionately large vertical stretching of the basal ice in the center of the ice stream since the basal ice is warmer and much less viscous than the ice above a thickening of that layer would cause a corresponding increase of surface velocity we presume that this mechanism contributes to the fast flow of jakobshavns isbrae

the great lunar hot spot and the composition and origin of the apollo mafic lkfm impact melt breccias thorium rich mafic impact melt breccias from the apollo 14 17 missions that is those breccias identified with the composition known as lkfm are regarded largely as products of basin forming impacts that penetrated the feldspathic crust and sampled underlying mafic material and magma ocean residuum carrying the compositional signature of kreep potassium rare earth elements phosphorous despite considerable compositional variation among such breccias compositions of all of them correspond to mixtures of only four components 1 a norite with composition generally similar to that of apollo 15 basalt mean abundance 58 range 30 95 2 fo 90 dunite mean 13 range 1 27 3 feldspathic upper crust mean 29 range 4 50 and feni metal 0 1 1 7 petrographic evidence has shown that much of the feldspathic component but none of the kreep component is clastic this observation and the high proportion of kreep norite component in the breccias suggest that the melt zone of the impact or impacts forming the breccias contained little feldspathic material but consisted predominantly of material with the average composition of kreep norite the dunite component probably derives ultimately from the upper mantle these conclusions support the hypothesis that the breccias were not formed in typical feldspathic crust but instead by one or more impacts into what is designated here the great lunar hot spot that is the anomalous th rich terrane in the imbrium procellarum area identified by the apollo and lunar prospector gamma ray spectrometers the lkfm composition is a special product of the great lunar hot spot and is not the average composition of the lower crust in typical feldspathic highlands similarly mg suite and alkali suite plutonic rocks of the apollo collection are likely all differentiation products of the hot spot not of plutons that might occur in typical feldspathic crust

petrography geochronology and source terrain characteristics of lunar meteorites dhofar 925 961 and sayh al uhaymir 449 abstract dhofar dho 925 961 and sayh al uhaymir sau 449 are brecciated lunar meteorites consisting of mineral fragments and clasts from a range of precursor lithologies including magnesian anorthositic gabbronorite granulites crystalline impact melt breccias clast bearing glassy impact melt breccias lithic fragmental breccias mare basalts and evolved silica rich rocks on the similarity of clast type and mineral chemistry the samples are likely grouped and were part of the same parent meteorite phosphate pb pb ages in impact melt breccias and matrix grains demonstrate that dho 961 records geological events spanning 500 ma between 4 35 and 3 89 ga these pb pb ages are similar to the ages of ancient intrusive magmatic samples and impact basin melt products collected on the lunar nearside by the apollo missions however the samples bulk rock composition is chemically distinct from these types of samples and it has been suggested that they may have originated from the farside south pole aitken impact basin i e jolliff et al 2008 we test this hypothesis and conclude that although it is possible that the samples may be from the south pole aitken basin there are other regions on the moon that may have also sourced these complex breccias

the materials of the lunar procellarum kreep terrane a synthesis of data from geomorphological mapping remote sensing and sample analyses major features of the moon s procellarum kreep terrane include subdued relief and extensive resurfacing with mare basalt consistent with high concentrations of th and other heat producing elements at depth we relate the chemistry of sampled materials to the geomorphology th surface concentrations determined by the lunar prospector 2 pixels and feo and tio2 concentrations derived from clementine ultraviolet visible spectral data on the basis of geologic maps each pixel was classified as mare terra or mixed near the periphery of the terrane terra pixel compositions are relatively feldspathic in the interior they mainly represent imbrium basin rim or ejecta deposits and are mainly incompatible trace element rich norites and presumably represent materials from a thick section tens of kilometers of the pre imbrium crust of the terrane excavated by the imbrium event although imbrium ejecta are the principal source of surface terra materials the imbrium event did not create the th rich procellarum kreep terrane broad continuous expanses of mare pixels are observed with little interruption from protruding terra or terra penetrating craters the mare basalt dominated regoliths of these areas have a wide range of tio2 concentrations 18 leading to the conclusion that the high th concentrations are in the mare basalts and are not present in the regoliths as terra derived materials volcanic glasses and impact glasses of mare basalt composition collected from the procellarum kreep terrane support this conclusion

petrography mineralogy and trace element geochemistry of lunar meteorite dhofar 1180 here we report the petrography mineralogy and trace element geochemistry of the dhofar 1180 lunar meteorite dhofar 1180 is predominantly composed of fine grained matrix with abundant mineral fragments and a few lithic and glassy clasts lithic clasts show a variety of textures including cataclastic gabbroic granulitic ophitic subophitic and microporphyritic both feldspathic and mafic lithic clasts are present most feldspathic lithic clasts have a strong affinity to ferroan anorthositic suite rocks and one to magnesian suite rocks mafic lithic clasts are moderately to extremely fe rich the ti ti cr fe fe mg compositional trend of pyroxenes in mafic lithic clasts is consistent with that of low ti mare basalts glasses display a wide chemical variation from mafic to feldspathic some glasses are very similar to those from apollo 16 soils kreep components are essentially absent in dhofar 1180 one glassy clast is rich in k ree and p but its mg mg fe is very low 0 25 it is probably a last stage differentiation product of mare basalt molar fe mn ratios of both olivine and pyroxene are essentially consistent with a lunar origin

computing marine ice thickness at an ice shelf base the freezing of sea water to the base of an ice shelf can give rise to large patches of accumulated ice a phenomenon known as marine ice in this study a numerical method is presented for calculating the thickness of the marine ice layer using an ice shelf ocean model the present day modeling paradigm of ice shelf ocean interaction usually involves the fixed specification of the ice shelf geometry while the ocean circulation in the cavity beneath the ice shelf evolves freely this approach relies on several assumptions such as steady state ice shelf thickness and ice shelf flow fields in order to make reasonable quantitative estimates of the thermodynamic exchange processes occurring at the ice shelf base this paper discusses the impact of these and other assumptions on the estimation of the thickness of the marine ice layer model simulation results are presented for an idealized ice shelf ocean configuration as a demonstration of the feasibility of the numerical method a sensitivity analysis is given so as to quantify the relative uncertainty in the marine ice thickness that arises from uncertainties in the model input parameters these being principally the ice shelf flow field the basal accumulation rate and the ice shelf thickness field

textural characteristics and impurity content of meteoric and marine ice in the ronne ice shelf antarctica the texture and physical properties of an ice core recovered to 215 m depth from the ronne ice shelf antarctica have been studied with regard to formation and transformation of the ice at a depth of 152 8 m a sharp discontinuity marks the transition between meteoric ice accumulated from above and marine ice accreted from below as testified by electrolytical conductivity and stable isotope measurements as well as geophysical field surveys automated image analysis of thin sections indicates that the decrease in grain boundary density and the increase in grain cross sectional area with depth is commensurate with though not necessarily caused bythermodynamically driven grain growth down to 120m depth corresponding to a vertical strain of roughly 65 as computed with a simple temperature history particle path model the observed increase of grain boundary density i e a decrease of grain size with age in the marine ice is in part explained by the thermal history of this layer sediment inclusions at the top of the marine ice layer affect the observed grain boundary density profile by inhibiting grain growth and dynamic recrystallization this may allow some conclusions on the role of temperature particulate inclusions stress and strain rate in controlling the grain size evolution of deforming ice supplementing earlier laboratory experiments conducted at much shorter time scales salinities 0 026 parts per thousand brine volumes 0 09 0 2 parts per thousand and solid salt concentrations have been computed from electrolytical conductivity measurements mean of 51 0 x 10 6 s cm 1 for the marine ice an assessment of salt incorporation and desalination rates shows that these low salinities can at present only be explained by a unique densification mechanism of under water ice crystals at the base of the ice shelf

post wildfire erosion response in two geologic terrains in the western usa abstract volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western united states these volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics however by measuring the erosion response as the erodibility efficiency of water to detach and transport sediment on hillslopes and in channels the erosion response from different geologic terrains can be compared specifically the erodibility efficiency is the percentage of the total available stream power expended to detach remobilize or transport a mass of sediment erodibility efficiencies were calculated for the i initial detachment and for the ii remobilization and transport of sediment on the hillslopes and in the channels after wildfire in two different geological terrains the initial detachment efficiencies for the main channel and tributary channel in the granitic terrain were 10 9 and 5 4 and were similar to those for the volcanic terrain which were 5 5 and 1 1 no initial detachment efficiency could be measured for the hillslopes in the granitic terrain because hillslope measurements were started after the first major rainstorm the initial detachment efficiency in the volcanic terrain was 1 3 0 41 the average remobilization and transport efficiencies associated with flash floods in the channels also were similar in the granitic 0 18 0 57 and volcanic 0 11 0 41 terrains on the hillslope the remobilization and transport efficiency was greater in the volcanic terrain 2 4 than in the granitic terrain 0 65 however this may reflect the reduced sediment availability after the first major rainstorm 30 min maximum rainfall intensity 90 mm h 1 in the granitic terrain while easily erodible fine colluvium remained on the hillslope after the first rainstorm 30 min maximum rainfall intensity 7 2 mm h 1 in the volcanic terrain the erosion response in channels and on hillslopes of the granitic and volcanic terrains was similar when compared using erodibility efficiencies

evidence for basal marine ice in the filchner ronne ice shelf the filchner ronne ice shelf which drains most of the marine based portions of the west antarctic ice sheet is the largest ice shelf on earth by volume the origin and properties of the ice that constitutes this shelf are poorly understood because a strong reflecting interface within the ice and the diffuse nature of the ice ocean interface make seismic and radio echo sounding data difficult to interpret1 2 ice in the upper part of the shelf is of meteoric origin but it has been proposed2 5 that a basal layer of saline ice accumulates from below here we present the results of an analysis of the physical and chemical characteristics of an ice core drilled almost to the bottom of the ronne ice shelf we observe a change in ice properties at about 150 m depth which we ascribe to a change from meteoric ice to basal marine ice the basal ice is very different from sea ice formed at the ocean surface and we propose a formation mechanism in which ice platelets in the water column accrete to the bottom of the ice shelf

diverse impactors in apollo 15 and 16 impact melt rocks evidence from osmium isotopes and highly siderophile elements abstract concentrations of highly siderophile elements hse and 187 os 188 os isotopic compositions for eleven impact related rocks from the apollo 15 and 16 landing sites are reported and combined with existing geochronological data to investigate the chemical nature and temporal changes in the large impactors implicated in the formation of the lunar basins data for the samples all define linear trends on plots of hse versus ir concentrations whose slopes likely reflect the relative hse compositions of the dominant impactors that formed the rocks the inferred imbrium basin impactor that generated apollo 15 impact melt rocks 15445 and 15455 was characterized by modestly suprachondritic 187 os 188 os ru ir pt ir and pd ir ratios diverse impactor components are revealed in the apollo 16 impact melt rocks the 187 os 188 os and hse ir ratios of the impactor components in melt rocks 60635 63595 and 68416 with reported ages 4 0 ga by contrast the impactor components in melt rocks 60235 62295 and 67095 with reported ages of 3 9 ga are characterized by suprachondritic 187 os 188 os and hse ir ratios similar to the apollo 15 impact melt rocks and may also sample the imbrium impactor three lithic clasts from regolith breccias 60016 and 65095 also with 3 9 ga ages contain multiple impactor components of which the dominant composition is considerably more suprachondritic than those implicated for imbrium and serenitatis apollo 17 impactors the dominant composition recorded in these rocks was most likely inherited from a pre imbrium impactor consideration of composition versus age relations among lunar impact melt rocks reveals no discernable trend virtually all lunar impact melt rocks sampled by the apollo missions as well as meteorites are characterized by 187 os 188 os and hse ir ratios that when collectively plotted define linear trends ranging from chondritic to fractionated compositions the impact melt rocks with hse signatures within the range of chondritic meteorites are interpreted to have been derived from impactors that had hse compositions similar to known chondrite groups by contrast the impact melt rocks with non chondritic relative hse concentrations could not have been made by mixing of known chondritic impactors these signatures may instead reflect contributions from early solar system bodies with bulk chemical compositions that have not yet been sampled by primitive meteorites present in our collections alternately they may reflect the preferential incorporation of evolved metal separated from a fractionated planetesimal core pre 4 0 ga ages for at least some impactor components with both chondritic and fractionated hse raise the possibility that the bulk of the hse were added to the lunar crust prior to the later stage basin forming impacts such as imbrium and serenitatis as proposed by fischer godde and becker 2012 for this scenario the later stage basin forming impacts were more important with respect to mixing prior impactor components into melt rocks rather than contributing much to the hse budgets of the rocks themselves

petrogenesis of the northwest africa 4734 basaltic lunar meteorite we report the petrography mineralogy trace element abundance geochemistry and pb pb geochronology of the lunar meteorite northwest africa nwa 4734 and make a comparison with the lapaz icefield lap 02205 02224 low ti lunar basaltic meteorites nwa 4734 is an unbrecciated low ti mare basalt composed mainly of subophitic textured pyroxene 60 vol and plagioclase 30 pyroxene plagioclase and olivine exhibit large compositional variations and intra grain chemical zoning pyroxene and plagioclase in nwa 4734 have rare earth element ree concentrations and patterns similar to those of the laps the crystallization age of nwa 4734 determined in situ in baddeleyite is 3073 15 ma 2 sigma nearly identical to that of the laps 3039 12 ma nwa 4734 and the laps have similar textures modal abundances mineral chemistry and crystallization ages and are most likely source crater paired on the moon

the comparative behavior of apatite zircon u pb systems in apollo 14 breccias implications for the thermal history of the fra mauro formation we report secondary ion mass spectrometry sims u pb analyses of zircon and apatite from four breccia samples from the apollo 14 landing site the zircon and apatite grains occur as cogenetic minerals in lithic clasts in two of the breccias and as unrelated mineral clasts in the matrices of the other two sims u pb analyses show that the ages of zircon grains range from 4023 24 ma to 4342 5 ma whereas all apatite grains define an isochron corresponding to an age of 3926 3 ma the disparity in the ages of cogenetic apatite and zircon demonstrates that the apatite u pb systems have been completely reset at 3926 3 ma whereas the u pb system of zircon has not been noticeably disturbed at this time the apatite u pb age is slightly older than the ages determined by other methods on apollo 14 materials highlighting need to reconcile decay constants used for the u pb ar ar and rb sr systems we interpret the apatite age as a time of formation of the fra mauro formation if the interpretation of this formation as an imbrium ejecta is correct apatite also determines the timing of imbrium impact the contrast in the pb loss behavior of apatite and zircon places constraints on the temperature history of the apollo 14 breccias and we estimate from the experimentally determined pb diffusion constants and an approximation of the original depth of the excavated samples in the fra mauro formation that the breccias experienced an initial temperature of about 1300 1100 c but cooled within the first five to ten years

exposure matters forest dynamics reveal an early holocene conifer refugium on a north facing slope in central europe although several studies provide a broad overview of vegetation changes in the carpathian basin during the holocene stand scale vegetation changes are lesser known because of the rarity of suitabl

lateral podzolization in a sandstone catchment a sandstone catchment of the cool perhumid black forest germany was studied with respect to podzolization processes on a landscape scale soil mapping along a steep slope 25 revealed spodosols with thick e horizons combined with thin spodic horizons in the upper catchment area lowermost parts of the landscape showed thinnest e and thickest bhs horizons this catenary trend was quantified by a non linear increase of the illuviation eluviation ratio of podzolization ierpodzol soil texture pedogenic oxides feo fed alo mnd ph cacl2 corg and mineralogical composition of the clay and medium sand fraction were determined in six representative pedons chemical analysis matched morphology in that very low contents and mass densities of feo fed alo and mnd were found in upslope soils the distal pedons were 2 5 fold higher in these elements the catenary trends corresponded to a downslope increase in ph as well as organic carbon in mineral soils mineralogical analysis showed a decrease in feldspar weathering and an increase in hydroxy interlayered vermiculites towards the downslope soils the morphological chemical and mineralogical results led to the conclusion of a process sequence of i an upslope mobilization and depletion of iron manganese and aluminum e spodosols ii a lateral translocation 30 of catchment discharge occurred as interflow and iii a downslope immobilization resulting in a relative or absolute accumulation of the translocated soil compounds bs spodosols the immobilization probably was controlled by an admixture of fe and base richer rocks into the parent material downslope the concept of lateral podzolization developed in a granite landscape was confirmed in the sandstone area studied

the pace of holocene vegetation change testing for synchronous developments mid to high latitude forest ecosystems have undergone several major compositional changes during the holocene the temporal and spatial patterns of these vegetation changes hold potential information to their causes and triggers here we test the hypothesis that the timing of vegetation change was synchronous on a sub continental scale which implies a common trigger or a step like change in climate parameters pollen diagrams from selected european regions were statistically divided into assemblage zones and the temporal pattern of the zone boundaries analysed the results show that the temporal pattern of vegetation change was significantly different from random times of change cluster around 8 2 4 8 3 7 and 1 2 ka while times of higher than average stability were found around 2 1 and 5 1 ka compositional changes linked to the expansion of corylus avellana and alnus glutinosa centre around 10 6 and 9 5 ka respectively a climatic trigger initiating these changes may have occurred 0 5 to 1 ka earlier respectively the synchronous expansion of c avellana and a glutinosa exemplify that dispersal is not necessarily followed by population expansion the partly synchronous partly random expansion of a glutinosa in adjacent european regions exemplifies that sudden synchronous population expansions are not species specific traits but vary regionally

mineralogy petrology and shock history of lunar meteorite sayh al uhaymir 300 a crystalline impact melt breccia sayh al uhaymir sau 300 comprises a microcrystalline igneous matrix grain size s4 the association of maskelynite with melt pockets and shock veins indicates a subsequent local 28 45 gpa shock stage s2 s3 excursion which was probably responsible for lofting the sample from the lunar surface subsequent fracturing is attributed to atmospheric entry and probable breakup of the parent meteor

the bombardment history of the moon as recorded by 40 ar 39 ar chronology new petrography and 40ar 39ar ages have been obtained for 1 3 mm sized rock fragments from apollo 16 station 13 soil 63503 north ray crater ejecta and chips from three rocks collected by apollo 16 and apollo 17 missions selection of these samples was aimed at the old 40ar 39ar ages to understand the early history of the lunar magnetic field and impact flux fifteen samples were studied including crustal material polymict feldspathic fragmental breccias and impact melts the impact ages obtained range between approximately 3 3 and 4 3 billion years ga polymict fragmental breccia 63503 1 exhibits the lowest signs of recrystallization observed and a probable old relic age of 4 547 0 027 the plateau age of 4 293 0 044 ga obtained for impact melt rock 63503 13 represents the oldest known age for such a lithology possibly this age represents the minimum age for the south pole aitken spa basin in agreement with literature data these results show that impact ages 3 9 ga are found in lunar rocks especially within soil 63503 impact exhumation of deep seated warm crustal material onto the lunar surface is considered to explain the common 4 2 ga ages obtained for weakly shocked samples from soil 63503 and apollo 17 this would directly imply that one or more basin forming events occurred at that time some rock fragments showing none to limited petrologic features indicate thermal annealing these rocks may have lost ar while resident within the hot ejecta of a large basin concurrent with previous studies these results lead us to advocate for a complex impact flux in the inner solar system during the initial approximately 1 3 ga

borehole evidence for a thick layer of basal ice in the central ronne ice shelf the ronne ice shelf floating between berkner island and the antarctic peninsula is the biggest ice shelf in antarctica it drains an estimated 1 2 106km2 of the antarctic ice sheet much of it resting on bedrock below sea level consequently the balance and dynamics of this ice shelf is of importance to antarctic glaciology especially with regard to the integration of this part of the cryo sphere into the global processes that control the climate of the earth extensive radio echo sounding res by robin and others revealed reflections in the central part of the ronne ice shelf at the relatively shallow depth of 100 200 m below surface1 the interpretation of these echoes which varied in strength was ambiguous and the possibility of internal reflecting horizons was thoroughly discussed but after surface elevation measurements by radar altimeter from drifting balloons appeared to fit the presence of thin ice it was decided to base a thickness map of the ronne ice shelf on these res echoes1 4 we now present direct observational evidence from boreholes that the total ice thickness is much greater than mapped and that the shallow res reflections therefore do come from internal horizons

relative and absolute ages of individual craters and the rate of infalls on the moon in the post imbrium period abstract this paper contains a reasonably successful attempt to determine relative ages and then absolute ages of individual craters younger than imbrium and the rate of infalls onto the moon as a function of time after the tail of the massive premare bombardment became depleted before 3 aeons 1 aeon 109 years ago there was a period of minimal numbers of infalls the rate of infalls increased rather steadily from this minimum to the present the rate in the geologically recent past 0 3 aeon was about two times that found for the period immediately after the last of the major lave outpourings 3 2 aeons absolute ages were determined for large craters 8 km from crater counts on the surfaces within and on the rims of the large craters key dates were 0 and 0 3 aeon for terrestrial meteoritic craters 3 2 3 5 3 8 and 3 82 aeons for the various mare surfaces according to the determinations of d e wilhelms 1980 geologic history of the moon u s geol surv prof pap and 3 85 aeons from the formation of imbrium

late glacial and holocene sequences in rockshelters and adjacent wetlands of northern bohemia czech republic correlation of environmental and archaeological records this paper combines complex archaeological records from excavations of sandstone rockshelters with paleobotanical investigations in the adjacent wetlands of northern bohemia czech republic several pollen diagramms from nearby peatbogs are used to document the paleoenvironmental development from the late glacial to the middle holocene in addition two recently excavated key archaeological sections were selected to document human behavioral responses to the climatic development kostelni rokle and smoln kamen this region remained mostly unsettled during the upper paleolithic magdalenian or epigravettian so that the late paleolithic colonization after the lgm appears to be a major behavioral adaptation the early and middle mesolithic foragers developed this pattern to be optimally adapted to the versatile landscape of sandstone plateaus and canyons during the holocene the aim was to exploit its changing vegetational aquatic and terrestric faunal resources until the late mesolithic