highland contamination in lunar mare soils improved mapping with multiple end member spectral mixture analysis mesma 1 multiple end member spectral mixture analysis mesma was applied to the clementine uvvis global 1 km multispectral data set and the resulting highland material fraction image was used to investigate highland contamination of mare surfaces by impact cratering mesma decomposes each pixel with the number of end members fewer than the number of the spectral bands of clementine uvvis data this allows the use of variable end member combinations to accommodate global spectral variance a 13 end member set of lunar soil components that spans the lunar spectral diversity was selected from the uvvis data and included 1 mature and 4 fresh highland soils 4 mature and 2 fresh mare soils and 2 soils of dark mantling materials this set was applied to the lunar data through mesma and an aggregated global highland abundance was derived comparison of the highland fraction results from mesma and traditional spectral mixture analysis sma demonstrated that mesma better accommodates the compositional variation of mare soils resulting in a greater accuracy in the measurement of highland with the derived products we investigated highland contamination in mare nectaris mare fecunditatis and mare crisium these mare surfaces are proximal to the large craters theophilus taruntius langrenus and proclus and provided an opportunity to investigate highland contamination by large impacts the analyses indicated that theophilus impact resulted in highland contamination of 20 80 on most of mare nectaris while taruntius and langrenus impacts caused 5 40 contamination of mare fecunditatis the trend of minimal highland abundance in mare fecunditatis correlates poorly with basalt thickness suggesting an efficient lateral mixing due to the large craters taruntius and langrenus additionally proclus combining with other craters was responsible for highland contamination in most of the mare crisium surface and some basalt classification in this mare reflects highland contamination of the spectral properties mesma significantly reduces uncertainty in calculating global composition variations due to mixing and these analyses demonstrate that large impacts played a dominant role in delivering highland materials onto three mare surfaces

the shape and internal structure of the moon from the clementine mission global topographic and gravitational field models derived from data collected by the clementine spacecraft reveal a new picture of the shape and internal structure of the moon the moon exhibits a 16 kilometer range of elevation with the greatest topographic excursions occurring on the far side lunar highlands are in a state of near isostatic compensation whereas impact basins display a wide range of compensation states that do not correlate simply with basin size or age a global crustal thickness map reveals crustal thinning under all resolvable lunar basins the results indicate that the structure and thermal history of the moon are more complex than was previously believed

distinguishing high alumina mare basalts using clementine uvvis and lunar prospector grs data mare moscoviense and mare nectaris 1 high alumina ha mare basalts are a unique group of the lunar sample collection sample geochemistry indicates that these basalts are derived from sources composed of late stage cumulates from the lunar magma ocean lmo their aluminous nature suggests their sources contained significant plagioclase which has implications regarding the efficiency of plagioclase separation from earlier forming mafic cumulates in the lmo to form the anorthositic lunar crust and hence the heterogeneity of the lunar mantle the apollo and luna missions sampled ha basalts from four different locations that are separated by 80 equatorial degrees 2400 km radiometric age dating of these samples demonstrates aluminous basaltic volcanism spanned over 1 billion years suggesting ha basalts may be more prevalent on the moon than implied by the sample population knowing their global occurrence would ultimately enhance our understanding of lunar evolution aluminous mare basalts occupy a unique location in th feo compositional space that suggests they can be identified using global remote sensing data of the moon we present our approach for distinguishing exposures of ha basalts using clementine ultraviolet visible infrared uvvis and lunar prospector gamma ray spectrometer lp grs data with constraints based on the feo tio2 and th abundances of apollo and luna ha samples we identified 34 regions of interest rois where ha basalts could be a prominent component of the lunar surface by analyzing the rims and proximal ejecta from small impacts 0 4 4 km in diameter into the mare surface we characterized compositionally distinct basaltic units that make up the mare and thus determined which units represent ha basalt lavas the results were used to generate maps that depict discrete mare units and classify their general basalt type here we focus on two rois mare moscoviense and mare nectaris mare moscoviense is composed of four basaltic units two of which are ha candidates clementine uvvis data of mare nectaris show evidence of up to three mare basalt units one is the remnants of a mid ti unit that capped earlier low ti flows the majority of the basin is filled by a compositionally indistinguishable low fe low ti basalt however spectral profiles suggest there are two units regardless the units both fit the criteria for a ha basalt

new views of lunar geoscience an introduction and overview beyond the earth the moon is the only planetary body for which we have samples from known locations the analysis of these samples gives us ground truth for numerous remote sensing studies of the physical and chemical properties of the moon and they are invaluable for our fundamental understanding of lunar origin and evolution prior to the return of the apollo 11 samples the moon was thought by many to be a primitive undifferentiated body e g urey 1966 a concept shattered by the data returned from the apollo and luna missions ever since new data have helped to address some of our questions but of course they also produced new questions in this chapter we provide a summary of knowledge about lunar geologic processes and we describe major scientific advancements of the last decade that are mainly related to the most recent lunar missions such as galileo clementine and lunar prospector 1 1 the moon in the planetary context compared to terrestrial planets the moon is unique in terms of its bulk density its size and its origin fig 1 1a c all of which have profound effects on its thermal evolution and the formation of a secondary crust fig 1 1d numerous planetary scientists considered the moon as an endmember among the planetary bodies in our solar system because its lithosphere has been relatively cool rigid and intact throughout most of geological time a one plate planet and its surface has not been affected by plate recycling an atmosphere water or life therefore the moon recorded and preserved evidence for geologic processes that were active over the last 4 4 5 b y and offers us the unique opportunity to look back into geologic times for which evidence on earth has long been erased fig 1 1c d impact cratering an exterior process is considered the most important surface process on the moon internal

modeling the provenance of the apollo 16 regolith 1 the regolith at the apollo 16 landing site the only apollo landing site in the central lunar highlands contains material derived from a number of sources a model that accounts for the introduction of basin ejecta and mixing of the megaregolith is used to estimate the abundance of basin material in the apollo 16 regolith megaregolith mixing model estimates of the abundance of primary ejecta from the imbrium serenitatis and nectaris basins are found to be present in roughly equal 8 10 proportions additionally the presence of mare derived material in the apollo 16 regolith suggests that a significant component of the regolith 15 23 is derived from lateral transport there are inherent difficulties in directly comparing model results with ground truth at apollo 16 results suggest shallower mixing during ejecta emplacement than predicted by oberbeck et al 1975

the nature of crater rays the copernicus example crater rays are formed during a cratering event as target material is ballistically ejected to distances of many crater radii forming narrow generally high albedo approximately linear features extending outward from the crater the nature of crater rays was examined for the lunar crater copernicus using new information on the composition of surface material from near ir reflectance measurements surface roughness from radar backscatter measurements and photogeologic data from available images part of the data analysis included use of mixing models to quantify the mixing systematics observed between primary ejecta and local substrate of the ray on the basis of compositional parameters from reflectance spectra primary material from copernicus can be detected in the surface material of rays in decreasing amounts with increasing radial distance e g 20 25 primary ejecta at six crater radii for distances greater than three crater radii the proportion of local material to primary ejecta observed from these compositional reflectance data is approximately equal to that predicted by previous laboratory and ballistic studies of craters within three crater radii the compositional data indicate a higher proportion of primary ejecta than predicted for extended areas along the ray that do not contain large secondary craters the primary ejecta is intimately mixed on the granular scale with local material throughout the regolith the relatively high albedo of the rays of copernicus is due to the feldspathic composition highland of the primary ejecta in rays emplaced on a mare substrate immature local substrate is only observed in copernicus s ray at large unmantied secondary craters or other areas with sufficient topographic slope to prevent the accumulation of mature soils crater rays are filamentous generally high albedo features that emanate nearly radially from young impact structures rays are narrow in relation to the crater radius extend distally for many crater radii and constitute a distinctive albedo feature around some of the largest and freshest lunar craters visible from earth synoptic views of ray systems figure la give the strong impression that the rays comprise bright material that has been excavated from the crater cavity and been emplaced beyond the continuous ejecta deposit if this visual impression is correct then the process that forms crater rays represents a significant mechanism for the lateral transport of primary material to great distances from its point of origin and particularly for craters larger than a let tens of kilometers in diameter constitutes a fundamental process for the regional mixing of crustal materials earth based telescopic images of the moon allowed the first studies and descriptions of rays and ray systems shoemaker 1962 described the arcuate and loop shaped streaks of the copernicus ray systems and showed that these patterns could be locally resolved into individual en echelon feather shaped elements 15 20 km in length with their long axes oriented approximately radially to the crater he noted the presence of elongate depressions or gouges in the ray system ranking in diameter from 8 km down to the limits of resolution and generally located at the proximal ends of the individual ray elements shoemaker observed that some of the gouges were

a combined spectrophotometric and morphometric study of the lunar mare dome fields near cauchy arago hortensius and milichius in this study we examine the spectral and morphometric properties of the four important lunar mare dome fields near cauchy arago hortensius and milichius we utilize clementine uv vis mulfispectral data to examine the soil composition of the mare domes while employing telescopic ccd imagery to compute digital elevation maps in order to determine their morphometric properties especially flank slope height and edifice volume after reviewing previous attempts to determine topographic data for lunar domes we propose an image based 3d reconstruction approach which is based on a combination of photoclinometry and shape from shading accordingly we devise a classification scheme for lunar marc domes which is based on a principal component analysis of the determined spectral and morphometric features for the effusive mare domes of the examined fields we establish four classes two of which are further divided into two subclasses respectively where each class represents distinct combinations of spectral and morphometric dome properties as a general trend shallow and steep domes formed out of low tio2 basalts are observed in the hortensius and milichius dome fields while the domes near cauchy and arago that consist of high tio2 basalts are all very shallow the intrusive domes of our data set cover a wide continuous range of spectral and morphometric quantities generally characterized by larger diameters and shallower flank slopes than effusive domes a comparison to effusive and intrusive mare domes in other lunar regions highland domes and lunar cones has shown that the examined four mare dome fields display such a richness in spectral properties and 3d dome shape that the established representation remains valid in a more global context furthermore we estimate the physical parameters of dome formation for the examined domes based on a rheologic model each class of effusive domes defined in terms of spectral and morphometric properties is characterized by its specific range of values for lava viscosity effusion rate and duration of the effusion process for our data set we report lava viscosities between about 10 2 and 10 8 pas effusion rates between 25 and 600 m 3 s 1 and durations of the effusion process between three weeks and 18 years lava viscosity decreases with increasing r 415 r 750 spectral ratio and thus tio2 content however the correlation is not strong implying an important influence of further parameters like effusion temperature on lava viscosity

insights into circum arctic sea ice variability from molecular geochemistry abstract geological records of past sea ice such as those contained in arctic marine sediments offer an opportunity to strengthen our understanding of long term sea ice variability provided unambiguous paleo sea ice proxies can be developed one such recently proposed proxy is ip25 a highly branched isoprenoid alkene biosynthesized exclusively by sea ice dwelling diatoms haslea spp which is well preserved in marine sediments and could be used to reconstruct past changes in spring sea ice extent however little is known about regional scale controls on ip25 production in sea ice limiting its wider applicability as a paleo sea ice proxy to address this issue we examined the distributions of ip25 and the marine productivity biomarkers dinosterol and brassicasterol in a suite of surface sediment samples distributed across the arctic we find a statistically significant logarithmic relationship between ip25 and spring sea ice cover in sediment samples from arctic and subarctic sites in the pacific n 96 r2 0 67 p

the clementine mission to the moon scientific overview in the course of 71 days in lunar orbit from 19 february to 3 may 1994 the clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths these data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side in addition laser ranging measurements provided the first view of the global topographic figure of the moon the topography of many ancient impact basins has been measured and a global map of the thickness of the lunar crust has been derived from the topography and gravity

mariner 10 multispectral images of the eastern limb and farside of the moon we present the first analysis of mariner 10 multispectral image data for the eastern limb and farside of the moon a new rigorous calibration of these data is used that provides results that are consistent with independently derived data sets from these newly calibrated data a color ratio image 0 48 0 58 m is produced to show relative tio2 abundances in mare units on the eastern limb and farside of the moon our results indicate that the farside lunar mare deposits examined have tio2 contents that are intermediate to low 2 5 tio2 relative to mare deposits on the nearside we find no evidence for areally extensive deposits of either very low titanium vlt or high to very high titanium vht basalts in these portions of the moon our findings support previous interpretations that the source regions for lunar mare basalts are laterally heterogeneous additionally examination of highland units reveals a relatively blue region that corresponds with a previously proposed cryptomare suggesting enhanced tio2 for this unit finally based on these mariner 10 data telescopic spectral data galileo multispectral image data and lunar meteorite analyses we speculate that volcanism in farside mare deposits did not include high titanium basalts 8 wt

variability of sea surface temperature and sea ice cover in the fram strait over the last two millennia abstract a sediment core located on the west spitzbergen margin in the fram strait 78 54 931 n 6 46 005 e water depth 1497 m was analyzed for its dinocyst content in order to reconstruct hydroclimatic variations of the last 2500 years the relative abundance of dinocyst taxa and principal component analysis show a major transition at about 300 cal years bp it is characterized by the disappearance of thermophilic taxa spiniferites mirabilis hyperacanthus and impagidinium sphaericum and the increase of polar subpolar taxa impagidinium pallidum and pentapharsodinium dalei sea surface temperature sst estimates suggest warmer conditions than present anomaly 2 c averaging at 7 c in summer until 300 cal years bp although cooling pulses are recorded around 1700 1500 1200 and 800 cal years bp the last 300 years were marked by a cooling from 7 6 to 3 5 c and sea ice cover increasing up to 7 months yr the results demonstrate that the fram strait area is sensitive to hydroclimatic variations notably with respect to sea ice and ssts which are linked to the relative strength of northward flow of north atlantic waters to the east and southward outflow of cold and fresh waters from the arctic ocean based on our data the warmest part of our record around 1320 cal years bp is the only interval of the last 2500 years that provides a possible analogue for the modern post ad 2000 interval which is characterized by sea ice free conditions

on lateral mixing efficiency of lunar regolith 1 to reexamine the potential for lateral mixing over large distances 100 km by impact craters a mathematical model utilizing the stable probability distribution is proposed for estimating lateral mixing efficiency on the moon the proposed model divides material mixing into shallow slope and steep slope regimes mixing in the shallow slope regime conforms to the condition that the exponent of the power law describing lunar crater size frequency is larger than the exponent of the power law describing the rim thickness plus 2 otherwise the mixing is called the steep slope regime the model suggests that in the shallow slope regime lateral mixing on the moon is efficient enough to deliver 20 30 exotic components over distances greater than 100 km e g highland material to the mare the model indicates that lateral mixing conforming to the steep slope regime is not efficient if linear addition of ejecta deposits is assumed because in this regime impact cratering is driven by small craters reworking lunar surface and the addition of crater ejecta is an invalid assumption if the result of the proposed model for the shallow slope regime is applied to regolith layers below the reworked zone a significant number of exotic components is predicted

on lunar asymmetries 2 origin and distribution of mare basalts and mascons 1 a novel mechanism is proposed for the emplacement of mare basalts and the formation of mascons that does not involve melting or remelting of the source region the source magmas are the remnants of the primordial lunar magma ocean and are rich in incompatible elements including radioactive isotopes potassium rare earth elements and phosphorus kreep and volatiles exsolution of volatiles as the magmas cooled and crystallized a process called second boiling produced overpressures which drove the dense basalts upward to the surface creating the mascons this process occurred preferentially beneath nearside mare basins where the crust is thinnest and lithostatic pressure is lowest the delay between impact and magmatic extrusion reflects the time needed for the volatile rich magma to cool to its second boiling point radioactive heating buffered the magmas against cooling and solidification allowing for an extended period of magmatism

identification of contrasting seasonal sea ice conditions during the younger dryas abstract a palaeo sea ice reconstruction for northern norway for the interval ca 13 8 7 2 cal ka bp has been performed using a combined organic geochemical proxy based study of a marine sediment core jm99 1200 obtained from andfjorden 69 15 95 n 16 25 09 e and the outcomes compared with a series of other palaeoclimate studies carried out previously within this study particular emphasis has been placed on the identification of the sea ice conditions during the younger dryas and the application of different biomarker based proxies to both identify and quantify seasonal sea ice conditions firstly the appearance of the specific sea ice diatom proxy ip 25 at ca 12 9 cal ka bp in the sedimentary record has provided an unambiguous but qualitative measure of seasonal sea ice and thus the onset of the younger dryas stadial the near continuous occurrence of ip 25 for the next ca 1400 yr demonstrates seasonal sea ice during this interval although variable abundances suggest that the recurrent conditions in the early mid younger dryas ca 12 9 11 9 cal ka bp changed significantly from stable to highly variable sea ice conditions at ca 11 9 cal ka bp and this instability in sea ice prevailed for the subsequent ca 400 yr during which an extremely short interval of permanent or near permanent sea ice was observed at ca 11 75 cal ka bp at ca 11 5 cal ka bp ip 25 disappeared from the record indicating ice free conditions that signified the beginning of the holocene the ip 25 concentrations were also combined with those of the open water phytoplankton biomarker brassicasterol to generate p b ip 25 data from which more quantitative measurements of sea ice were determined p b ip 25 data were consistent with consecutively seasonal then infrequent sea ice cover for the early mid and late younger dryas while further comparisons of the p b ip 25 data with the outcomes of previous correlations with modelled sea ice concentrations suggested that these intervals were characterised by ca 60 90 and ca 0 60 sea ice cover respectively both qualitative and quantitative sea ice records were also consistent with sea surface temperature and other palaeoclimate estimates derived previously from various other proxy studies the contrasting seasonal sea ice conditions during the younger dryas were further verified through a comparison of the concentrations of ip 25 with those of another highly branched isoprenoid hbi alkene that is di unsaturated and believed to also be produced by sea ice diatoms the ratio of the hbi diene to ip 25 termed dip 25 is believed to provide a useful indicator of stability or variability in sea ice conditions and complements the outcomes from the ip 25 and p b ip 25 index data the identification of contrasting seasonal sea ice conditions during the younger dryas will likely contribute to the debate regarding the climatic impacts that took place during this intriguing interval

reconstruction of sea surface conditions at middle to high latitudes of the northern hemisphere during the last glacial maximum lgm based on dinoflagellate cyst assemblages abstract a new calibration database of census counts of organic walled dinoflagellate cyst dinocyst assemblages has been developed from the analyses of surface sediment samples collected at middle to high latitudes of the northern hemisphere after standardisation of taxonomy and laboratory procedures the database comprises 940 reference data points from the north atlantic arctic and north pacific oceans and their adjacent seas including the mediterranean sea as well as epicontinental environments such as the estuary and gulf of st lawrence the bering sea and the hudson bay the relative abundance of taxa was analysed to describe the distribution of assemblages the best analogue technique was used for the reconstruction of last glacial maximum lgm sea surface temperature and salinity during summer and winter in addition to sea ice cover extent at sites from the north atlantic n 63 mediterranean sea n 1 and eastern north pacific n 1 three of the north atlantic cores from the continental margin of eastern canada revealed a barren lgm interval probably because of quasi permanent sea ice six other cores from the greenland and norwegian seas were excluded from the compilation because of too sparse assemblages and poor analogue situation at the remaining sites n 54 relatively close modern analogues were found for most lgm samples which allowed reconstructions the new lgm results are consistent with previous reconstructions based on dinocyst data which show much cooler conditions than at present along the continental margins of canada and europe but sharp gradients of increasing temperature offshore the results also suggest low salinity and larger than present contrasts in seasonal temperatures with colder winters and more extensive sea ice cover whereas relatively warm conditions may have prevailed offshore in summer from these data we hypothesise low thermal inertia in a shallow and low density surface water layer

buried stratigraphic relationships along the southwestern shores of oceanus procellarum implications for early lunar volcanism the composition of mare highland boundaries is investigated in the region of southwestern oceanus procellarum using multispectral images from the galileo solid state imaging system the data are analyzed using a linear image based spectral mixture model to map the distribution and abundance of spectral end members representing mare basalt mature highland soils and fresh crater materials the fraction images that result from the mixture modeling are then integrated into a geographic information system database to analyze the relationship between the compositional gradients and regional geologic and geomorphic units within this framework three basic types of mixing gradients are recognized narrow mixing zones broad mixing zones and complex mixing zones the narrow zones appear to be the result of simple postformation lateral mass transport of surface materials due to the time averaged effects of impact cratering and regolith gardening the broad or moderate mixing zones exhibit evidence for significant incorporation of basalt into the distal basin ejecta of orientale and thus are interpreted to indicate that pre orientale volcanism and volcanic deposits were widespread in the procellarum region this is further corroborated by the mare rich ejecta blanket observed for the 100 km diameter impact crater letronne the complex mixing zones show evidence for extensive pre orientale and perhaps pre imbrium cryptomare as well as some volcanism extending into the late imbrian period these results indicate that mare highland boundaries frequently contain a convolved geologic record that allows insight into the geologic events prior to the final one apparently recorded by surface deposits for this region of the moon we now recognize that volcanism was well established and widespread in early imbrian time but had become more focused to a few major volcanic regions humorum procellarum by the late imbrian

sea ice variations in the central canadian arctic archipelago during the holocene abstract a sea ice record for barrow strait in the canadian arctic archipelago caa is presented for the interval 10 0 0 4 cal kyr bp this holocene record is based primarily on the occurrence of a sea ice biomarker chemical ip25 isolated from a marine sediment core obtained from barrow strait in 2005 a core chronology is based on 14c ams dating of mollusc shells obtained from ten horizons within the core the primary ip25 data are compared with complementary proxy data obtained from analysis of other organic biomarkers stable isotope composition of bulk organic matter benthic foraminifera particle size distributions and ratios of inorganic elements the combined proxy data show that the palaeo sea ice record can be grouped according to four intervals and these can be contextualised further with respect to the holocene thermal maximum htm spring sea ice occurrence was lowest during the early mid holocene 10 0 6 0 cal kyr bp and this was followed by a second phase 6 0 4 0 cal kyr bp where spring sea ice occurrence showed a small increase between 4 0 and 3 0 cal kyr bp spring sea ice occurrence increased abruptly to above the median and we associate this interval with the termination of the htm elevated spring sea ice occurrences continued from 3 0 to 0 4 cal kyr bp although they were more variable on shorter timescales within this fourth interval we also provide evidence for slightly lower and subsequently higher spring sea ice occurrence during the mediaeval warm period and the little ice age respectively comparisons are made between our proxy data with those obtained from other palaeo climate and sea ice studies for the caa

seeking a holocene drift ice proxy non clay mineral variations from the sw to n central iceland shelf trends regime shifts and periodicities quantitative x ray diffraction analysis of the 2 mm sediment fraction was carried out on 1257 samples from the seafloor and 16 cores from the iceland shelf west of 18 w all but one core b997 347pc were from transects along troughs on the nw to n central shelf an area that in modern and historic times has been affected by drift ice the paper focuses on the non clay mineralogy of the sediments excluding calcite and volcanic glass quartz and potassium feldspars occupy similar positions in an r mode principal component analysis and oligoclase feldspar tracks quartz these minerals are used as a proxy for ice rafted detritus ird accordingly the sum of these largely foreign minerals q k to icelandic bedrock is used as a proxy for drift ice a stacked equi spaced 100 a record is developed which shows both low frequency trends and higher frequency events the detrended stacked record compares well with the flux of quartz mg cm 2 a 1 at md99 2269 off n iceland the multi taper method indicated that there are three significant frequencies at the 95 confidence level with periods of ca 2500 445 and 304 a regime shift analysis pinpoints intervals when there was a statistically significant shift in the average q k weight and identifies four ird rich events separated by intervals with lower inputs there is some association between peaks of ird input less dense surface waters from 18o data on planktonic foraminifera and intervals of moraine building copyright 2009 john wiley sons ltd

climate induced changes in sedimentary regimes for organic matter supply on the continental shelf off northern norway abstract with this study i suggest that changes in biogeochemical processes in northern norwegian fjords during the last glacial interglacial transition 14 3 to 6 3 ka b p are predominantly climate induced variable strength in atlantic water inflow intrusion of arctic waters and sea ice coverage various nutrient supply as well as several re advances of continental ice sheets are recorded by both bulk organic and selected biomarkers in sediments of the andfjord stable isotope 13corg 15n and rock eval pyrolysis data indicate a strong supply of terrestrial organic matter during stadials e g younger dryas older dryas whereas enhanced input of marine organic matter prevailed during the interstadials bolling allerod profiles of selected biomarkers of marine origin show a characteristic climate induced variation during the whole time interval where relatively low concentrations of dinosterols and c37 alkenones may indicate similar to today a minor contribution of their respective plankton groups coccolithophorids dinoflagellates the prevalence of arctic waters and seasonal sea ice coverage during the younger dryas is indicated by a single maximum of 24 methylenecholesterol probably indicating the dominance of sea ice diatoms and or the prevalence of diatoms of thalassiosiraceae in surface waters the sediments of the allerod in contrast show a pronounced maximum in dinosterols indicating a better adaptation of dinoflagellates to an oceanic regime that is characterized by incipient intrusion of atlantic water highly variable sea surface temperatures and well stratified water masses the concentration of higher molecular weight n alkanes however follows the deglacial early holocene trend of climate amelioration from the last deglaciation to the middle holocene with maxima during ice advances stadials and minima during the middle holocene warm period these new results significantly improve the understanding of climate induced response on organic matter supply in fjords and provide a better knowledge of past variations of biogeochemical processes in high latitude coastal environments

historical variability of sea ice edge position in the nordic seas 1 historical ice observations in the nordic seas from april through august are used to construct time series of ice edge position anomalies spanning the period 1750 2002 while analysis showed that interannual variability remained almost constant throughout this period evidence was found of oscillations in ice cover with periods of about 60 to 80 years and 20 to 30 years superimposed on a continuous negative trend the lower frequency oscillations are more prominent in the greenland sea while higher frequency oscillations are dominant in the barents the analysis suggests that the recent well documented retreat of ice cover can partly be attributed to a manifestation of the positive phase of the 60 80 year variability associated with the warming of the subpolar north atlantic and the arctic the continuous retreat of ice edge position observed since the second half of the 19th century may be a recovery after significant cooling in the study area that occurred as early as the second half of the 18th century

the isotopic record of lunar volcanism abstract the timing and extent of lunar volcanism was determined primarily by the internal thermal evolution of the moon a late heavy bombardment produced most of the observable lunar basins easily recognized stratigraphic markers and also may have influenced lunar volcanism most of the nearside basins seem to have been produced 3 8 4 0 ga ago during a period often referred to as the lunar cataclysm the pre cataclysm period was characterized by formation of the lunar crust plutonic rocks within the crust and pre mare volcanism isotopic analysis of breccia clasts pre dating the cataclysm has yielded an outline of this period the isotopic record of post cataclysm mare volcanism is clear but incomplete because samples from the youngest mare areas are lacking specifically the isotopic data show that some lunar anorthosites formed 4 45 ga ago consistent with early formation of an anorthositic lunar crust some mg suite norites troctolites and dunites also formed approximately contemporaneously with the oldest anorthosites but others are up to 200 300 ma younger more evolved rocks granites and quartz monzodiorites also formed between 4 4 and 4 0 ga ago the earliest known pre mare volcanism at 4 25 ga ago included aluminous mare like basalts and an olivine gabbronorite similar to apollo 12 basalts kreep basalt volcanism began at least 4 1 ga ago approximately contemporaneously with that of the ancient mare like basalts and continued during the cataclysm recorded instances of high ti mare basalt volcanism began during or immediately after the cataclysm low ti mare basalt volcanism is the most recent for which samples are available the isotopic data record an early primary lunar differentiation during which mare basalt sources formed probably by crystallization of cumulus minerals from a lunar magma ocean the isotopic record of post cataclysm basalts indicates a heterogeneous lunar mantle and can be explained by partial melting of cumulate sources but more complex petrogenesis also has been suggested more complex petrogenetic processes including assimilation and assimilation fractional crystallization afc seem to be required for pre mare volcanics the isotopic data contain a hint that petrogenesis of the oldest pre mare volcanics may be linked to formation of the so called procellarum basin possibly the oldest and largest lunar basin such a basin would provide a geologic context for the pre mare volcanics and its formation may have been a defining moment in lunar history

230th normalization an essential tool for interpreting sedimentary fluxes during the late quaternary there is increasing evidence indicating that syndepositional redistribution of sediment on the seafloor by bottom currents is common and can significantly affect sediment mass accumulation rates notwithstanding its common incidence this process generally referred to as sediment focusing is often difficult to recognize if redistribution is near synchronous to deposition the stratigraphy of the sediment is not disturbed and sediment focusing can easily be overlooked ignoring it however can lead to serious misinterpretations of sedimentary fluxes particularly when past changes in export flux from the overlying water are inferred in many instances this problem can be resolved at least for sediments deposited during the late quaternary by normalizing to the flux of 230th scavenged from seawater which is nearly constant and equivalent to the known rate of production of 230th from the decay of dissolved 234u we review the principle advantages and limitations of this method notwithstanding its limitations it is clear that 230th normalization does provide a means of achieving more accurate interpretations of sedimentary fluxes and eliminates the risk of serious misinterpretations of sediment mass accumulation rates

formation of lunar mare domes along crustal fractures rheologic conditions dimensions of feeder dikes and the role of magma evolution abstract in this study we examine a set of lunar mare domes located in the hortensius milichius t mayer region and in northern mare tranquillitatis with respect to their formation along crustal fractures their rheologic properties the dimensions of their feeder dikes and the importance of magma evolution processes during dome formation many of these domes display elongated summit vents oriented radially with respect to major impact basins and several dome locations are also aligned in these preferential directions analysis of clementine uv vis and lunar prospector gamma ray spectrometer data reveals that the examined mare domes formed from low si basaltic lavas of high feo and low to moderate tio2 content based on their morphometric properties diameter height volume obtained by photoclinometric and shape from shading analysis of telescopic ccd images we derive rheologic quantities lava viscosity during eruption effusion rate duration of the effusion process magma rise speed and the dimensions of the feeder dikes we establish three rheologic groups characterised by specific combinations of rheologic properties and dike dimensions where the most relevant discriminative parameter is the lava viscosity the first group is characterised by 10 4 pa s 10 6 pa s and contains the domes with elongated vents in the milichius t mayer region and two similar domes in northern mare tranquillitatis the second group with 10 2 pa s 10 4 pa s comprises the very low aligned domes in northern mare tranquillitatis and the third group with 10 6 pa s 10 8 pa s the relatively steep domes near hortensius and in the t mayer region the inferred dike dimensions in comparison to lunar crustal thickness data indicate that the source regions of the feeder dikes are situated within the upper crust for six of the domes in northern mare tranquillitatis while they are likely to be located in the lower crust and in the upper mantle for the other examined domes by comparing the time scale of magma ascent with the time scale on which heat is conducted from the magma into the host rock we find evidence that the importance of magma evolution processes during ascent such as cooling and crystallisation increases with lava viscosity we conclude that different degrees of evolution of initially fluid basaltic magma are able to explain the broad range of lava viscosities inferred for the examined mare domes the spectral data reveal that differences in tio2 content may additionally account for the systematic difference in lava viscosity between the two examined lunar regions we show that the described mechanisms are likely to be valid also for other lunar mare domes situated near cauchy and arago regarded for comparison on the other hand we find for the gruithuisen and mairan highland domes that despite their inferred high lava viscosities of 10 8 10 9 pa s no significant magma cooling in the dike occurred during ascent supporting previous findings that the highland domes were formed during a specific phase of non mare volcanism by highly silicic viscous lavas

mid latitude southern indian ocean response to northern hemisphere heinrich events abstract the lack of temporal resolution and accurate chronology of southern ocean marine cores has hampered comparison of glacial millennial scale oscillations between the southern ocean antarctic ice and other records from both hemispheres in this study glacial climate variability is investigated over the last 50 ka using a multi proxy approach a precise chrono stratigraphy was developed on the high sedimentation rate core md94 103 indian southern ocean 45 35 s 86 31 e 3560 m water depth by geomagnetic synchronization between the later core and napis75 and 14c dates high resolution time series of 18o in planktonic foraminifera globigerina bulloides and neogloboquadrina pachyderma and sea surface temperatures ssts estimated from the alkenone uk 37 index and foraminifera assemblages have been generated temporal evolution of the two temperature proxy records is notably different during the last glacial period while foraminifera data indicate a consistent cooling towards the last glacial maximum anomalous warm glacial alkenone temperatures suggest a strong advection of warm detrital alkenones by surface waters of the agulhas current superimposed to this general trend during heinrich events foraminiferal ssts point to warmer surface waters while concurrent alkenone ssts exhibit apparent coolings probably caused by enhanced local alkenone production by analogy to modern observations possible influence of enso like conditions on the subantarctic southern ocean ssts is discussed

the origin and evolution of lunar high ti basalts periodic melting of a single source at mare tranquillitatis abstract five groups of basalts a b1 b2 b3 d with three principal ages exist at the apollo 11 site these range from the low k low rare earth element ree groups b1 b2 and b3 to the low k high ree group d basalts to the high k high ree group a basalts the group a basalts are the only high k 0 2 wt k2o basalts and youngest with an age of 3 59 02 ga groups b3 and b1 are 3 71 02 and 3 67 02 ga respectively group b2 basalts are the oldest at 3 85 02 ga group d basalts have not been dated fractionation modelling for major and trace elements indicates that the b1 basalts could have formed from a b3 like parent liquid the b2 and d basalts can also be related to liquids similar to the b3 b1 composition through the presence of varying amounts of modal whitlockite thus the entirety of low k high ti basalts at apollo 11 may have formed through melting of the same source region the group a basalt compositions are consistent with formation from a different parent liquid with the composition of apollo 11 orange glass modelling of major and trace elements in the apollo 11 orange glass indicate that the composition of the group a basalts is consistent with fractionation of this glass coupled with some assimilation 7 5 15 of an evolved kreep like material however this component is much younger than primitive kreep 4 4 ga this neukreep component similar to the composition of quartz monzodiorites described from the apollo 15 site probably represents evolved material formed during plutonism prior to the formation of the apollo 11 orange glass liquid

a new look at the apollo 11 regolith and kreep although the apollo 11 mission landed in mare tranquillitatis 50 km from the nearest exposure of highlands small nonmare particles are conspicuous in the regolith the nonmare portion of the apollo 11 regolith is compositionally similar to the apollo 16 regolith at both sites most of the nonmare material is from the feldspathic highlands but some is mafic impact melt breccia with the chemical signature known as kreep for its high concentrations of k rare earth elements and p the composition of the apollo 11 regolith corresponds best to a mixture of 66 crystalline mare basalt 5 orange volcanic glass 20 material of the feldspathic highlands 8 kreep bearing impact melt breccia and 1 meteoritic material the volcanic glass and kreep bearing melt breccia components account for the high concentrations of mg and cr in the regolith the most kreep rich sample known from apollo 11 10085 1187 is an impact melt breccia that bears a strong textural and compositional similarity to a unique apollo 16 melt breccia 64815 although not of the maria such breccias are also not of the highlands provenance global data obtained from orbit show that kreep bearing materials are most common at low elevations in the imbrium procellarum region and are rare at high elevations thus as at apollo 16 the kreep bearing breccias of apollo 11 are probably ejecta from the imbrium impact into the low lying procellarum kreep terrane on the basis of these observation and others we suggest that the general acceptance of kreep as a material of the highlands is not supported by the data and results largely from historical accident

recent sediment accumulation rates for the western margin of the barents sea abstract we investigate patterns processes and rates of sediment accumulation within the marginal ice zone of the western barents sea the barents sea is among the most productive of the arctic marginal seas with approximately half of the sediment burial flux derived from marine rather than terrestrial sources sediment accumulation rates were quantified by 210 pb geochronology at 14 stations ranging in water depths from 173 to 503 m along a south north latitudinal gradient of 6 75 81 n the average sediment accumulation rate for all stations is 0 7 0 4 mm yr in general lower sediment accumulation rates are associated with coarser sediment fractions at shallower water depths 200 m where currents remove fine grained sediments and transport material to the deeper regions higher sediment accumulation rates are detected in deeper water stations and are largely associated with specific sedimentation events and or features of the barents seafloor although the c n ratio of surface sediments 0 2 cm from all stations indicates a predominance of sediments of marine origin c n 9 0 1 0 there is no distinct depositional pattern indicating preferential burial in areas more heavily influenced by the marginal ice zone we conclude that a combination of mixed sediment sources large shifts in the location of the marginal ice zone over time and the benthic boundary layer processes obscure the productivity signal preserved in these seafloor sediment deposits of the western barents sea

the arctic sea ice biomarker ip25 a review of current understanding recommendations for future research and applications in palaeo sea ice reconstructions in recent years a novel proxy for the past occurrence of arctic sea ice has been proposed that is based on the variable marine sedimentary abundance of an organic geochemical lipid derived from sea ice diatoms in the spring this lipid termed ip25 ice proxy with 25 carbon atoms is a highly branched isoprenoid mono unsaturated alkene that appears to be sufficiently stable in sediments to permit meaningful palaeo sea ice reconstructions to be carried out over short to long term timescales since the first proposed use of ip25 as a proxy for palaeo sea ice by belt et al 2007 a number of laboratories have measured this biomarker in arctic sediments and it is anticipated that research activity in this area will increase further in the future the content of this review is divided into a number of sections firstly we describe the scientific basis for the ip25 proxy and its initial discovery in arctic sea ice sedimenting particles and sediments secondly we summarise the relatively few studies that have to date concentrated on examining the factors that influence the production and fate of ip25 and we identify some areas of future research that need to be addressed in order to improve our understanding of ip25 data obtained from sedimentary analyses what is clear at this stage however it that the presence of ip25 in arctic marine sediments appears to represent a proxy measure of past seasonal sea ice rather than permanent or multi year ice conditions thirdly we highlight the importance of rigorous analytical identification and quantification of ip25 especially if measurements of this biomarker are going to be used for quantitative sea ice reconstructions rather than qualitative analyses alone presence absence fourthly we review some recent attempts to make the interpretations of ip25 biomarker data more detailed and quantitative by combining sedimentary abundances with those of phytoplankton and other sea ice derived biomarkers thus the bases for the so called pip25 and dip25 indices are described together with an overview of potential limitations concluding that investigations into the use of these indices needs further research before their full potential can be realised in the final section we provide a summary of ip25 based palaeo sea ice reconstruction case studies performed to date these case studies cover different arctic regions and timescales spanning decades to tens of thousands of years

mineralogy of the last lunar basalts results from clementine the last major phase of lunar volcanism produced extensive high titanium mare deposits on the western nearside which remain unsampled by landing missions the visible and near infrared reflectance properties of these basalts are examined using clementine multispectral images to better constrain their mineralogy a much stronger 1 m ferrous absorption was observed for the western high titanium basalts than within earlier maria suggesting that these last major mare eruptions also may have been the most iron rich these western basalts also have a distinctly long wavelength 1 m ferrous absorption which was found to be similar for both surface soils and materials excavated from depth supporting the interpretation of abundant olivine within these deposits spectral variation along flows within the imbrium basin also suggests variations in ilmenite content along previously mapped lava flows as well as increasing olivine content within subsequent eruptions

stratigraphy and composition of lava flows in mare nubium and mare cognitum three major periods of basaltic activity characterize the infill of the basins each of these periods was itself punctuated by discrete phases of widespread magma eruptions three during both the late imbrian epoch and the early eratosthenian period and then two in the late eratosthenian period we found the youngest lavas off the eastern border of the fra mauro peninsula and mantling a much larger area over most of the central western nubium basin our results place the nubium cognitum basalts in the low ti category 1 5 wt tio2 the data indicate that the majority 90 of the mare terrain has iron content between 18 and 22 wt in particular feo contents tend to concentrate toward two compositional poles each of 20 wt and a much smaller one of 15 wt these values are typical of nearside lunar maria to complement our compositional data we present a census of craters larger than 500 m using orbiter iv images the result was a crater count average with frequency 5 6 10 2 km 2 translating into an inferred mean age of 3300 ma for the exposed lava flows by combining lava chemistry with age we find a possible correlation between the ages of the most prominent flow units and their estimated titanium content with younger basalts becoming progressively ti richer with time from 2 3 to 4 5 wt tio2

spectral properties of the marius hills volcanic complex and implications for the formation of lunar domes and cones we have used multispectral data from the clementine uv visible camera to study the volcanic features of the marius hills complex and their comparison to other lunar domes and cones there are several mare units identified in the complex each with a unique ti content as indicated by their 415 750 nm value the domes in marius hills are spectrally identical to the mare plains of the complex supporting similar compositions in contrast most of the volcanic cones of the complex are lower in reflectance bluer in color and have weaker mafic absorptions than the mare and domes the spectral characteristics of the cones can best be explained by fine grained crystallization in the spatter that compose the cones other lunar cones such as mons esam in northern tranquillitatis have spectral properties similar to those at marius hills the rima parry cones and their associated dark mantle deposit appear redder with a stronger mafic absorption than the marius hills cones the cones isis and osiris in southern mare serenitatis the domes of rumker hills and several domes in northern mare tranquillitatis are spectrally similar to adjacent mare units the mairan and gruithuisen domes in northern oceanus procellarum have a feldspathic signature characteristic of highland material although they are redder and brighter than adjacent highland soils they appear to represent highland material that resembles domes rather than actual mare domes like those at marius and rumker hills the diversity of lunar volcanic features can best be explained by differences in accumulation rates and cooling of ejected clasts from various eruption styles mare domes may have formed at lower effusion rates thereby allowing lava to construct small shields with slopes 3 the steeper domes at marius hills require higher viscosities resulting from even lower effusion rates and enhanced crystallization in the magmas during the terminal stages of earlier eruptions that emplaced the mare cones like mons esam rima parry isis and osiris are aligned along linear rilles and are interpreted to result from degassing of near surface dikes in contrast the cones of marius hills show no linear alignment and may result from strombolian eruptions at the terminal stages of earlier effusive eruptions that emplaced the domes and mare in the complex

crustal diversity of the moon compositional analyses of galileo solid state imaging data the multispectral images of the lunar limb and farside obtained by the solid state imaging ssi system on board the galileo spacecraft provide the first new pulse of compositional data of the moon by a spacecraft in well over a decade the wavelength range covered by ssi filters 0 4 1 0 m is particularly sensitive to the composition of mare basalts the abundance of mafic ferrous minerals and the maturity of the regolith to a first order the limb and farside material is consistent with previous characterization of nearside lunar spectral types for mare and highland soils and craters most basalts are of an intermediate tio 2 composition and most of the highland crust is feldspathic with local variations in mafic content identified principally at impact craters dark manfling material on the farside can be interpreted in terms of known properties of lunar pyroclastic glass regions of cryptornate are shown to have spectral properties intermediate between those of highland and mare soils as would be expected from a mixture of the two there are several important exceptions and surprises however unlike the basalt types identified on the nearside limb and farside basalts exhibit an exceptionally weak 1 xm ferrous absorption band this may indicate a compositionally distinct lunar basalt group that for example is more mg rich than most basalts of the nearside some of the most notable compositional anomalies are associated with south pole aitken basin this large region has a much lower albedo than surrounding highlands the inner darkest portion of the basin exhibits optical properties indistinguishable low ti basalts deposits to the south exhibit unique properties with a strong and broad ferrous 1 xrn absorption most consistent with abundant olivine the unusual compositions associated with south pole aitken and their spatial e3tent suggests the impact creating this huge lunar basin excavated mafic rich lower crust or perhaps mantle material 1 intro oucri ion

stratigraphy evolution and volume of basalts in mare serenitatis abstract fourteen major basaltic units in mare serenitatis have been identified and mapped from differences in tio2 wt the ages of these units have been inferred from their crater densities and reference to isotopically dated apollo samples it has been found that feo and tio2 wt of the units do not show any apparent trend with time however the oldest units have much greater variation in feo and tio2 wt than younger ones no lateral trend in the age of the basaltic units is apparent within the basin a vertical profile of mare serenitatis has been produced based on the depth of basalt within impact craters the minimum depth of basalt has been estimated where craters have not exposed underlying highland material the profile has been used to estimate the minimum volume of basalt within the basin to be 500 000 km3

remote sensing studies of the dionysius region of the moon 1 the dionysius region is located near the western edge of mare tranquillitatis and is centered on dionysius crater which exhibits a well developed dark ray system proposed origins for these dark rays included impact melt deposits and dark primary ejecta the region also contains extensive deposits of cayley type light plains clementine multispectral images and a variety of spacecraft photography were utilized to investigate the composition and origin of geologic units in the dionysius region the portions of the dark rays for which spectral and chemical data were obtained are composed of mare debris contaminated with minor amounts of highland material both five point spectra and values of the optical maturity omat parameter indicate that the dark rays are dominated by mare basalts not glassy impact melts the high albedo rays associated with dionysius exhibit feo and tio2 values that are lower than those of the adjacent dark ray surfaces and omat values that indicate that bright ray surfaces are not fully mature the high albedo rays are bright largely because of the contrast in albedo between ray material containing highlands rich ejecta and the adjacent mare rich surfaces the mafic debris ejected by dionysius was derived from a dark iron rich unit exposed high on the inner wall of the crater this layer probably represents a mare deposit that was present at the surface of the preimpact target site with one possible exception there is no evidence for buried mare basalts associated with cayley plains in the region

distribution and stratigraphy of basaltic units in maria tranquillitatis and fecunditatis a clementine perspective maria tranquillitatis and fecunditatis have been mapped based on clementine image mosaics and derived iron and titanium maps impact craters served as stratigraphic probes enabling better delineation of compositionally different basaltic units determining the distribution of subsurface basalts and providing estimates of total basalt thickness and the thickness of the surface units collected data indicate that volcanism in these maria started with the eruption of low ti basalts and evolved toward medium and high ti basalts some of the high ti basalts in mare tranquillitatis began erupting early and were contemporaneous with the low and medium ti basalts these units form the oldest units exposed on the mare surface mare tranquillitatis is mostly covered with high ti basalts in mare fecunditatis the volume of erupting basalts clearly decreased as the ti content increased and the high ti basalts occur as a few patches on the mare surface the basalt in both maria is on the order of several hundred meters thick and locally may be as thick as 1600 m the new basalt thickness estimates generally fall within the range set by earlier studies although locally differ the medium to high ti basalts exposed at the surfaces of both maria are meters to tens of meters thick

stratified ejecta boulders as indicators of layered plutons on the moon abstract high resolution images of stratified ejecta boulders on the lunar nearside reveal layers of alternating low and high albedo material we measured the thickness and albedo of each alternating light and dark layer from 29 stratified boulders located in aristarchus crater and mare undarum the results were used to test hypotheses to explain the origin of the observed strata in these impact ejected boulders morphologically these boulders demonstrate cross bedding trough shaped layering tapered layering and cumulate enclaves we interpret these characteristics to be evidence that these layers result from periodic disruption by convection or density currents within a cooling layered igneous intrusion we demonstrate that the layering observed in these boulders cannot be the result of known processes occurring on the surface but instead suggests a history of complex intrusive igneous processes within the lunar crust

ages of mare basalts on the lunar nearside the chronology of lunar volcanism is based on radiometric ages determined from apollo and luna landing site samples regional stratigraphic relationships and crater degradation and size frequency distribution data for units largely defined prior to the end of the apollo program here we report on new crater size frequency distribution data for 139 spectrally and morphologically defined basalt units which are exposed in six nearside impact basins australe tranquillitatis humboldtianum humorum serenitatis and imbrium crater size frequency distribution measurements are a statistically robust and accurate method to derive absolute model ages of unsampled regions of the moon compared to crater degradation ages crater size frequency ages performed on spectrally defined units offer significant improvements in accuracy our investigation showed that 1 in the investigated basins lunar volcanism was active for at least 1 5 2 0 b y starting at about 3 9 4 0 b y and ceasing at 2 0 b y 2 most basalts erupted during the late imbrian period at about 3 6 3 8 b y 3 significantly fewer basalts were emplaced during the eratosthenian period 4 basalts of copernican age were not found in any of the investigated basins 5 lunar basin filling volcanism probably started within 100 m y after the formation of the individual basins we also assessed the relationship between impact basin age and the history of mare basalt emplacement in these basins we found that 1 in all pre nectarian basins australe and tranquillitatis as well as in the humboldtianum basin which is of nectarian age the distribution of surface ages is clearly dominated by only a single peak in the number of erupted units at 3 6 3 8 b y 2 in the younger basins humorum serenitatis and imbrium a second peak at 3 3 3 5 b y is observed 3 basalt eruptions younger than 2 6 b y occur only intermittently and 4 in the youngest basins serenitatis and imbrium we see an extended period of active basin filling volcanism 1 5 1 6 b y which is 500 m y longer than in the australe and humorum and even 1 0 b y longer than in tranquillitatis and humboldtianum

lunar mare volcanism stratigraphy eruption conditions and the evolution of secondary crusts abstract lunar mare basalt deposits cover 17 of the lunar surface occur preferentially in topographic lows on the nearside and have a total volume estimated at 1 107 km3 analysis of returned samples and photogeologic and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment the period of cryptomare formation in pre nectarian times and continued until the copernican period a total duration approaching 3 5 4 ga stratigraphic analyses show that the flux was not constant but peaked in early lunar history during the imbrian period which spans the period 3 85 3 2 ga average volcanic output rate during this peak period was about 10 2 km 3 a very low relative to the present global terrestrial volcanic output rate and comparable to the present local output rates for individual volcanoes such as vesuvius and kilauea hawaii volcanic landforms indicate that many eruptions were of high volume and long duration some eruptions associated with sinuous rules may have lasted of the order of a year and emplaced 103 km3 of lava representing the equivalent in one year of about 70 000 years at the average flux shallow magma chambers were uncommon the nearsidefarside mare deposit asymmetry can be readily explained by differences in crustal thickness magma ascending from the mantle or from a buoyancy trap at the base of the crust should preferentially extrude to the surface on the nearside but should generally stall and cool in dikes in the farside crust extruding only in the deepest basins the occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation dikes that establish pathways to the surface on the nearside should have very high volumes comparable to the volumes associated with many observed flows and sinuous rilles an abundance of dikes should exist in the lower crust of the moon many more than those feeding surface eruptions the upper limit is 37 50 of the crust by volume the presence and abundance of such dike swarms have important implications for the interpretation of the average composition of the lunar crust and the composition of basin and crater ejecta the interplay between thermal contraction and differentiation leads to net cooling and ultimate contraction of the outer portions of the moon resulting in a regional horizontal compressive stress acting on the lunar crust in addition overall cooling and deepening of sources require the production of ever larger volumes of magma in order to reach the surface with time stresses became high enough so that few dikes could open to the surface causing eruptive activity to be severely diminished in the eratosthenian and perhaps to cease in the copernican period lower stress levels are required to terminate eruptive activity on the lunar farside consistent with the imbrian age of the farside maria and the nearside location of the youngest maria lunar mare deposits provide an example of the transition from primary crusts to secondary crusts and illustrate the significance of several factors in the evolution of secondary crusts such as crustal density variations in crustal thickness presence of impact basins state and magnitude of stress in the lithosphere and general thermal evolution these factors are also responsible for the extremely low volcanic flux even during periods of peak extrusion

variability of sea ice conditions in the fram strait over the past 30 000 years sea ice is a critical component of the climate and oceanographic system in the north atlantic ocean a biomarker record reveals millennial scale and glacial interglacial fluctuations in sea ice coverage in the northernmost atlantic ocean over the past 30 000 years

geological mapping and chronology of lunar landing sites apollo 11 abstract crater size frequency distribution csfds measurements allow the derivation of absolute model ages amas for geological units across various terrestrial bodies in the solar system based on body specific adjustments to the lunar chronology e g hartmann 1970 neukum et al 1975 1983 2001 stoffler and ryder 2001 stoffler et al 2006 hiesinger et al 2012 robbins 2014 thus it is important to revisit and test the accuracy of the lunar chronology using data from recent lunar missions e g hiesinger et al 2000 2012 2015 rajmon and spudis 2004 stoffler et al 2006 as well as newer analyses of lunar samples e g gaffney et al 2011 meyer 2012 snape et al 2016 welsh et al 2018 we generated a new detailed geological map of the apollo 11 landing region based on spectral characteristics topography and albedo maps which shows several mare units adjacent to the lunar module lunar reconnaissance orbiter camera lroc images were used to measure new csfds and derive the cumulative number of craters with diameters 1 km or n 1 for the apollo 11 landing site the newly derived n 1 values are consistent with the presence of only one surficial unit at the landing site the group a high k high potassium young mare basalt as described in meyer 2012 we reviewed the radiometric ages for apollo 11 samples that have been determined since the calibration of the lunar cratering chronology used our new geological map to reinterpret their provenance and correlated them with the new n 1 values these are plotted and compared with the lunar chronology of neukum et al 1983 our calibration point for the apollo 11 landing site is consistent with the earlier values thus confirming neukum s 1983 and neukum and ivanov s 2001 lunar chronology curves

lunar mare volcanism in the eastern nearside region derived from clementine uv vis data clementine uv vis multi spectral data were used to map mare deposits in the eastern lunar nearside region mare tranquillitatis mare fecunditatis mare serenitatis mare crisium mare nectaris to understand the volcanic history of this region an array of clementine and clementine derived data were used to classify mare basalts these include 750 nm albedo uv vis ratio 1 m absorption signatures and clementine derived feo and tio2 contents we have successfully identified several new geological units and have determined their spectral characteristics for example the relatively younger low ti basalts were recognized in the eastern part of mare tranquillitatis the central low ti basalts in mare serenitatis which had been classed as misp were divided into 2 groups in mare nectaris 2 types of mare basalts were identified while only 1 group was recognized in the previous study the stratigraphy constructed from the spectral analysis indicates that the mare deposits tend to become younger in the northern maria including serenitatis and crisium and older in the southern maria including tranquillitatis fecunditatis and nectaris according to the relationship between the titanium contents of the mare units and their stratigraphy the titanium content decreases with time in the early stage but increases toward the end of volcanism in the serenitatis and crisium region while it increases with time but finally decreases in the tranquillitatis and fecunditatis region in connection with the distribution of mare basalts a large amount of high ti mare basalts are found in mare tranquillitatis especially in the western part while other maria are covered by low ti basalts the iron contents show a similar distribution to that of titanium

basalt thickness in mare humorum the crater excavation method basalt thicknesses in mare basins have been determined using assumptions about the premare topography of partly buried craters and by comparison to the orientale basin differences in those assumptions have led to a factor of 4 difference in mare thickness estimates further knowledge of thickness is restricted to areas in which buried craters are present using mixing models applied to multispectral images acquired by the clementine spacecraft we have shown that craters in the mare sometimes excavate highland material from below the mare cover using such craters and assumptions about their depth of excavation we obtain independent estimates of basalt thickness our results are in agreement with the lowest of previous thickness estimates we derive a volume of 40 000 km 3 for basalts in mare humorum considerably less than the 110 000 km 3 from previous estimates we also confirm a diameter of 425 km for thc humorum multiring basin based on the clementine gridded global topography assuming an original morphology like orientale

a sharper view of impact craters from clementine data the ultraviolet visible camera on the clementine spacecraft obtained high spatial resolution images of the moon in five spectral channels impact craters mapped with these multispectral images show a scale of lithologic diversity that varies with crater size and target stratigraphy prominent lithologic variations feldspathic versus basaltic occur within the south wall of copernicus 93 kilometers in diameter on the scale of 1 to 2 kilometers lithologic diversity at tycho 85 kilometers in diameter is less apparent at this scale although the impact melt of these two large craters is remarkably similar in this spectral range the lunar surface within and around the smaller crater giordano bruno 22 kilometers in diameter is largely dominated by the mixing of freshly excavated material with surrounding older soils derived from a generally similar feldspathic lithology

mapping recent sea ice conditions in the barents sea using the proxy biomarker ip25 implications for palaeo sea ice reconstructions abstract an analysis of the sea ice proxy ip 25 and the open water phytoplankton indicator brassicasterol has been carried out for 93 surface sediments collected from the barents sea and some additional data from previous studies have been included to augment the analysis further consistent with a specific and selective sea ice diatom origin for ip 25 this biomarker was identified in virtually all sediments from seasonally ice covered locations but was absent from the majority of sites beyond the maximum sea ice extent msie for the period 1983 2002 in contrast brassicasterol was detected in virtually all sediments from the region and concentrations were not at all associated with the msie instead more localised regions of brassicasterol concentrations were identified and these likely reflect different influences on production and deposition when the ip 25 and brassicasterol concentrations were combined together in the form of the previously proposed p b ip 25 index the aforementioned association between ip 25 occurrence and the msie was clarified further and in addition provided more detailed descriptions of sea ice cover in particular p b ip 25 data indicated seasonal sea ice or marginal ice zone conditions for the region of the barents sea within the msie according to previously defined p b ip 25 ranges we also amalgamated the biomarker data from the current study with those derived previously by muller et al 2011 and compared these larger datasets with satellite derived mean spring sea ice concentrations significantly although the correlation between the combined ip 25 concentration dataset with the satellite data was very similar to that reported previously by muller et al 2011 the corresponding correlation using the p b ip 25 values was poorer with the larger dataset and some possible reasons for this are discussed finally in a small number of cases ip 25 was identified in sediments somewhat distal from the msie and it is hypothesised that the occurrence of ip 25 in these sediments results from allochthonous input following sediment advection between shelf and trough environments this is the first reported example that provides evidence for the allochthonous input of ip 25 into marine sediments and it is recommended that this should be considered carefully when carrying out palaeo sea ice reconstructions based on the occurrence of this biomarker in the future

arctic ocean deep sea record of northern eurasian ice sheet history the sediment composition of deep sea cores from the central arctic ocean the fram strait and the yermak plateau was analyzed for several parameters to reconstruct the history of marine paleoenvironment and terrestrial glaciation in the last 200 000 years layers with high amounts of coarse terrigenous ice rafted debris ird and often high contents of smectite were deposited during extensive glaciations in northern eurasia when ice sheets reached the northern continental margins of the barents and kara seas and discharged icebergs into the arctic ocean intercalated layers with relatively low ird and smectite contents but abundant planktic foraminifers in the coarse fraction were deposited during periods of atlantic water inflow to the arctic ocean and seasonally open waters leads in a sea ice cover with only few icebergs in the arctic ocean high ird contents in the sediments reflect the presence of ice sheets on the kara and barents seas shelves and the hinterland during the entire oxygen isotope stage 6 ca 190 130 ka in substage 5b ca 90 80 ka at the stage boundary 5 4 around 75 ka and in late stage 4 early stage 3 ca 65 50 ka these results are in excellent correlation with those from recent field work in northern scandinavia european russia siberia and on the shelves relatively low amounts of ird in central arctic ocean sediments from the late weichselian glacial maximum ca 24 18 ka correlate well with the recent reconstruction of a very limited eastern ice sheet extension during this time oxygen and carbon isotope records of planktic foraminifers from the analyzed sediment cores show a number of prominent excursions which can be interpreted as evidence for freshwater events in the arctic ocean the synchroneity of freshwater events and ird input suggests a common source strongest events were associated with deglaciations of the barents and kara seas after the ice sheets had blocked the outflow of large rivers for several millennia the outflow of freshwater from large ice dammed lakes occurred at ca 130 80 75 and 52 ka freshwater events in the central arctic ocean during the last deglaciation ca 18 ka were relatively small compared to the previous events this indicates that during most of the late weichselian glacial maximum a river outflow from northern siberia to the arctic ocean was possible atlantic water inflow to the arctic ocean and seasonally open waters in the ice leads occurred during the interglacials ofoxygen isotope stage 1 and substage 5e during several interstadials stage 3 substages 5a and 5c and to a lesser degree within stadials and glacials stages 2 4 and 6 with the exception ofthe interglacials these periods were times ofstrong ice growth on the continents as revealed by terrestrial data the coincidence suggests that open waters in the arctic ocean and the nordic seas were an important moisture source in addition to more southerly sources which fostered the growth of ice sheets on northern eurasia

a novel chemical fossil of palaeo sea ice ip25 a unique and novel organic compound has been detected in sea ice samples from three locations in the canadian arctic thousands of kilometers apart it is likely that this biomarker is produced by diatoms living in the sea ice and we provide evidence which suggests that the compound a c25 monounsaturated hydrocarbon ip25 may be a specific sensitive and stable proxy for sea ice in sediments over at least the holocene since it has not been reported before we confirmed its identity by synthesis and used the synthesized compound as a reference for quantifying ip25 in a range of sediments from an east west transect in the canadian arctic the recent sediments are either seasonally covered with ice or have permanent ice cover older sediments containing ip25 have been dated using radiocarbon methods to at least 9000 yr if the concept proves generally applicable monitoring ip25 in further sediment cores along with other accepted proxies should allow movements in the position of the ice edge throughout the holocene at least to be better determined which is essential for accurate calibration of climate prediction models a similar approach for antarctic samples of ice and sediments would also seem worthwhile

lunar cryptomaria physical characteristics distribution and implications for ancient volcanism cryptomaria lunar volcanic deposits obscured by crater and basin impact ejecta can provide important information about the thermal and volcanic history of the moon the timing of cryptomare deposition has implications for the duration and flux of mare basalt volcanism in addition knowing the distribution of cryptomaria can provide information about mantle convection and lunar magma ocean solidification here we use multiple datasets e g m3 lola lroc diviner to undertake a global analysis to identify the general characteristics e g topography surface roughness rock abundance albedo etc of lunar light plains in order to better distinguish between ancient volcanic deposits cryptomaria and impact basin and crater ejecta deposits we find 20 discrete regions of cryptomaria covering approximately 2 of the moon which increase the total area covered by mare volcanism to 18 of the lunar surface comparisons of light plains deposits indicate that the two deposit types volcanic and impact produced are best distinguished by mineralogic data on the basis of cryptomaria locations the distribution of mare volcanism does not appear to have changed in the time prior to its exposed mare basalt distribution there are several hypotheses explaining the distribution of mare basalts which include the influence of crustal thickness mantle convection patterns asymmetric distribution of source regions kreep distribution and the influence of a proposed procellarum impact basin the paucity of farside mare basalts means that multiple factors such as crustal thickness variations and mantle convection are likely to play a role in mare basalt emplacement

thorium abundances on the lunar surface measurements of absolute thorium abundances on the lunar surface are presented using both the high and low altitude data taken with the lunar prospector gamma ray spectrometer an analysis of the uncertainties shows that the measured uncertainties are 7 g g are likely small area regions 150 km 2 using lunar topographic data we have shown that the thorium abundances in the lunar high lands and portions of south pole aitken spa basin are larger for lower elevations we have also studied a number of regions with anomalously high thorium abundances such as the northwestern region of spa basin the crater arago in western tranquillitatis and the compton belkovich region in the northeastern highlands the compton belkovich region appears to be enriched with evolved rocks such as alkali anorthosite and currently represents the only such extended region on the moon that has been identified in contrast tycho crater has very low thorium abundances which suggests that kreep was not assimilated at depth in this portion of the moon

compositional variability of the serenitatis tranquillitatis region of the moon from telescopic multispectral imaging and spectroscopy abstract we present results from a combined ccd multispectral imaging and near ir spectroscopic study of a region near the border between the mare serenitatis and mare tranquillitatis lunar impact basins we have detected and spatially mapped variations in mare tio 2 abundance in the degree of spectral maturity of impact craters and their ejecta blankets and in the level of fresh highlands contamination within mare units techniques employed include color ratio images image oriented linear mixing models and spectral band analyses specific findings include the detection of relatively fresh highlands materials in the craters tacquet and sulpicius gallus and in the central peak and floor of the crater plinius the detection of low tio 2 serenitatis like mare materials in a confined region of the ejecta from the crater dawes and the determination of immaturity rather than composition as the origin of the high albedo in the rectangular deposit surrounding dawes the combination of high spatial resolution imaging and high spectral resolution spectroscopy and the use of synthesizing techniques such as mixture modeling will provide valuable tools to optimize the scientific return from telescopic galileo clementine and other future lunar data sets

a rapid method for determining organic matter maturity using raman spectroscopy application to carboniferous organic rich mudstones and coals abstract a simple and rapid automated raman maturity method is calibrated using a suite of carboniferous organic rich mudstones and coals from the inch of ferryton 1 borehole in the midland valley of scotland sediments in the borehole have been thermally matured by intrusion of a quartz dolerite sill generating vitrinite reflectance vr values ranging from 0 5 to 6 0 vro calibration curves are tested on eight other uk wells penetrating carboniferous shales and coals in the midland valley and southern pennine basin the g band full width at half maximum g fwhm is the best raman parameter to estimate the thermal maturity of organic matter om in the oil and gas window 0 5 to 3 vro and has a very strong correlation with vro

evolution of the upper mantle of the earth s moon neodymium and strontium isotopic constraints from high ti mare basalts isotopic studies of mare basalts have led workers to conclude that their sources are heterogeneous on both large and small scales furthermore these studies have led workers to postulate that depletion within the lunar mantle occurred early in its evolution and was a result of accumulation of mafic minerals from a lree enriched magma ocean high ti basalts from the apollo 1 i and 17 landing sites and ilmenite basalts from apollo 12 are secondary evidence of this extreme early depletion event kreepy rocks are the complementary enriched component in the moon a total of fourteen high ti basalts have now been analyzed from the apollo 11 landing site for neo dymium and strontium isotopes a sm nd internal isochron on basalt 10058 yields an age of 3 70 0 06 ga similar to 40ar 39ar ages of other group b 1 basal a compilation of all previously determined ages on apollo 11 high ti basalts indicates four distinct phases of volcanism at 3 85 0 02 ga group b2 3 71 f 0 02 ga group b3 3 67 0 02 ga group bl and 3 59 f 0 04 ga group a whole rock sm nd isotopic data for all apollo 11 high ti basalts form a linear array which yields the age of the moon 4 55 f 0 30 ga a similar regression of all uncontaminated high ti basalts from the moon both apollo 11 and apollo 17 yields an age of 4 46 0 17 ga both arrays are interpreted as average source ages of the high ti basalts and are consistent with the formation of these sources by precipitation of cumulates from a magma ocean early in the history of the moon these new strontium and neodymium isotopic data coupled with previously published data are con sistent with a two component model for the upper mantle of the moon these two components include mafic adcumulates precipitated from a magma ocean prior to 4 4 ga and small amounts 2 of trapped kreepy late stage magma ocean differentiates the mafic adcumulate evolves from 4 5 ga with 47sm 44nd 0 318 and rb r 0 005 to extremely radiogenic neodymium isotopic ratios and very unradiogenic strontium isotopic ratios the kreepy trapped liquid has a 14 sm 44nd 0 168 and rb r 0 235 and thus evolves toward very unradiogenic neodymium and radiogenic strontium isotopic ratios because the kreepy trapped liquid is enriched in both rubidium and the rees by over an order of magnitude compared to the mafic adcumulate trapping of even small proportions of this liquid in the adcumulate will control the radiogenic isotopic composition of the source the apparent heterogeneity in the source regions of mare basalts could be caused by trapping of variable yet small proportions of this lile enriched liquid in the cumulate pile

mare tranquillitatis basalt emplacement history and relation to lunar samples galileo and clementine multispectral data of the mare tranquillitatis region have been analyzed to investigate the stratigraphy of basaltic units and the effects of lateral and vertical mixing processes within the mare the distribution of compositionally distinct mare units is observed to be correlated with previous uv vis ratio images although estimates of soil titanium contents are low in some areas as a result of mixing of local basalts with nonmare feldspathic materials basalt units identified by their spectral properties and spectral mixture analysis are compared with groups of apollo 11 samples defined by previous workers on the basis of age and chemistry spectral studies presented here indicate that the apollo 11 site lies at the edge of a localized western mare unit which includes the youngest and most titanium rich basalts in tranquillitatis apollo 11 high k high ti samples in southern tranquillitatis these basalts have been contaminated by a large degree of mixing with nonmare feldspathic materials nonmare materials near the apollo 11 site are attributed largely to crater rays from theophilus 100 km in diameter which is located approximately 300 km to the south a more extensive and stratigraphically older unit exposed near apollo 11 is related to the low k high ti apollo 11 samples and appears to extend as a coherent surface unit as far north as the apollo 17 site in southern serenitatis the distribution of this spectrally identified basalt unit supports petrologic and geochemical evidence for the grouping of the high ti low k apollo 11 and 17 basalt samples into the same regional volcanic events multispectral analysis of tranquillitatis deposits also identify low titanium basalts in the northeastern and southeastern portions of the basin that are older than the high ti basalts and are believed to be unsampled by apollo 11 several lines of evidence suggest that the cayley formation along the western tranquillitatis margin may indeed lie on top of an ancient mare deposit buried by imbrium basin ejecta e g a cryptomare deposit the distribution of vertically excavated feldspathic premare material within the mare provides information on the depth of the mare units and the proximity of the underlying basin topography compositional stratigraphy observed in both sets of multispectral data supports an asymmetric premare fill basin topography containing thicker basalts in the northwestern portion of the basin than previously predicted by crater flooding data

a long lived lunar core dynamo paleomagnetic measurements indicate that a core dynamo probably existed on the moon 4 2 billion years ago however the subsequent history of the lunar core dynamo is unknown here we report paleomagnetic petrologic and 40ar 39ar thermochronometry measurements on the 3 7 billion year old mare basalt sample 10020 this sample contains a high coercivity magnetization acquired in a stable field of at least 12 microteslas these data extend the known lifetime of the lunar dynamo by 500 million years such a long lived lunar dynamo probably required a power source other than thermochemical convection from secular cooling of the lunar interior the inferred strong intensity of the lunar paleofield presents a challenge to current dynamo theory

lunar impact basins and crustal heterogeneity new western limb and far side data from galileo multispectral images of the lunar western limb and far side obtained from galileo reveal the compositional nature of several prominent lunar features and provide new information on lunar evolution the data reveal that the ejecta from the orientale impact basin 900 kilometers in diameter lying outside the cordillera mountains was excavated from the crust not the mantle and covers pre orientale terrain that consisted of both highland materials and relatively large expanses of ancient mare basalts the inside of the far side south pole aitken basin 2000 kilometers in diameter has low albedo red color and a relatively high abundance of iron and magnesium rich materials these features suggest that the impact may have penetrated into the deep crust or lunar mantle or that the basin contains ancient mare basalts that were later covered by highlands ejecta

remote sensing of potential lunar resources 1 near side compositional properties new telescopic ccd multispectral imaging of the lunar near side and 330 870 nm spectroscopy of selected regions are presented as aids in estimating compositional differences relevant to locating potential lunar resources such as ilmenite fetio3 and solar wind implanted 3he and h conversion of 400 560 nm ccd ratio images to weight percent tio2 using a version of the charette et al 1974 empirical relation allows construction of a new tio2 abundance map for the lunar maria accurate to 2 wt ho2 this map provides a consistent view of tio2 distribution among mature mare soils and can be used to estimate areas potentially rich in ilmenite western mare tranquillitatis exhibits the highest tio2 abundances 8 wt followed by regions near flamsteed p and in northern oceanus procellarum a 950 560 nm ccd ratio mosaic of the full moon provides estimates of relative surface maturity on local scales as defined by the degree of agglutinate production due to micrometeorite impacts since high 3he concentrations are correlated with mature ilmenite rich soils a combination of relative surface maturity maps and tio2 abundance maps may be useful for estimating 3he and possibly h distribution on local scales while dark mantle materials are also potential sources of ilmenite 3he and h their compositional differences from mare soils prevent accurate remote mapping of their tio2 abundance and relative maturity reflectance spectra relative to a more rigorously defined ms 2 standard region of dark mantle materials and high tio2 mare areas exhibit previously undocumented near uv 350 nm changes in spectral slope apparently related to compositional variations determination of the primary lunar sites for resource utilization will be dictated by the future goals and priorities of the lunar resource program

compositional gradients across mare highland contacts importance and geological implication of lateral transport observations of mixing across mare highland contacts using high resolution clementine data allow a new assessment of the relative importance of vertical versus lateral mass transport on the moon at least at mare highland contact we analyze mare highland contacts in the grimaldi orientale and fecunditatis basins and tsiolkovsky crater through image based nonlinear spectral mixture modeling of clementine ultraviolet visible uv vis light spectrometer multi spectral data the mare in these regions differ in ages but they are characterized by having simple geological contacts the symmetric distribution of mare and highland soil constituents across their geological contact indicates that lateral transport is more efficient than deep vertical transport during the formation of the observed mixing zones observations across the lunar limb with the clementine uv vis filters show that there is a stray light component of scattered light across high contrast albedo boundaries however the magnitude and spatial properties of scattered light do not significantly affect the nature of compositional boundaries determined here since repetitive meteorite bombardment governs lateral transport across the geological contacts and is a random process a stochastic model is developed to describe this lateral transport analysis of the power decay law for crater ejecta thickness indicates that the high velocity ejecta travels long distances and follows a 3 power decay law this results in an infinite variance which requires an anomalous diffusion model since a classical diffusion model would be invalid mathematical modeling supports this result where it is shown that classical diffusion produces a relatively poor fit to profiles of material abundance while the anomalous diffusion model fits the profiles adequately these results indicate that high velocity ejecta dominates the formation of the observed compositional gradients while the ejecta near the crater rim is relatively less important on the basis of these ejecta distributions and the assumption of random impact cratering we derive a relationship that can be used as an index for relative age dating of geological contacts as well as for investigating cratering rates

remote sensing of potential lunar resources 2 high spatial resolution mapping of spectral reflectance ratios and implications for nearside mare tio2 content high spatial resolution maps illustrating variations in spectral reflectance 400 560 nm ratio values have been generated for the following mare regions 1 the border between southern mare serenitatis and northern mare tranquillitatis including the ms 2 standard area and apollo 17 landing site 2 central mare tranquillitatis 3 oceanus procellarum near seleucus and 4 southern oceanus procellarum around flamsteed we have also obtained 320 1000 nm reflectance spectra of several sites relative to ms 2 to facilitate scaling of the images and provide additional information on surface composition inferred tio2 abundances for these mare regions have been determined using an empirical calibration which relates the weight percent tio2 in mature mare regolith to the observed 400 560 nm ratio mare areas with high tio2 abundances are probably rich in ilmenite fetio3 a potential lunar resource the highest potential tio2 concentrations we have identified in the nearside maria occur in central mare tranquillitatis inferred tio2 contents for these areas are 9 wt and are spatially consistent with the highest tio2 regions mapped previously at lower spatial resolution we note that the morphology of surface units with high 400 560 nm ratio values increases in complexity at higher spatial resolutions new telescopic spectra of landing sites successfully reproduce the charette relation although we find that the 400 560 nm value is strongly a fimction of the sample area size the increased spectral contrast of the 400 730 nm ratio over the 400 560 nm ratio demonstrates the potential increased precision with which the 400 730 nm ratio might be used to estimate tio2 abundances comparisons have been made with previously published geologic maps lunar orbiter iv and ground based images and some possible morphologic correlations have been found between our mapped 400 560 nm ratio values and volcanic landforms such as lava flows mare domes and collapse pits

molecular stratigraphy a new tool for climatic assessment variations in sea surface temperatures over the past 500 000 years are inferred from the relative abundance behaviour of two organic compounds c37 alkenones over the upper 8 metres of a sediment core from the eastern equatorial atlantic this molecular record ascribed to contributions from prymnesiophyte algae correlates well with the variations in the 18 signal for the calcareous skeletons of certain planktonic foraminifera thus providing the first demonstration of a new stratigraphical technique which may be especially valuable where methods based on carbonate 18 fail

tsiolkovsky crater a window into crustal processes on the lunar farside mineralogy and distribution of rock types in the tsiolkovsky region of the lunar farside are evaluated in terms of crustal stratigraphy and evolution calibrated multispectral images from five orbits of clementine data provide compositional information at a scale that allows diverse geologic features to be analyzed and compared the entire region is seen to be highly anorthositic with outcrops of relatively pure anorthosite quite common the crater itself has excavated blocks of anorthosite and noritic anorthosite from the near surface highland crust often in a mixed jumble the central peaks of tsiolkovsky which have exhumed much deeper material however are composed of relatively pure anorthosite with olivine rich zones concentrated near the ridge crests boundaries between the anorthosite and olivine rich zones are sharp but spatial relations suggest the coherent olivine rich zone is relatively thin 1 km the composition of the mare material filling tsiolkovsky is shown to be low titanium basalt smaller exposures of mare basalt occur about one crater radius from the rim the crustal structure to 25 km in this region prior to the tsiolkovsky impact appears to be top to bottom a few kilometers of anorthositic breccias comprising the megaregolith a zone of crystalline anorthosite with pockets of noritic anorthosite a zone of anorthosite devoid of iron bearing minerals and a zone of relatively pure anorthosite containing olivine rich material possibly emplaced as intrusions

integrated spectral analysis of mare soils and craters applications to eastern nearside basalts abstract high spatial resolution clementine images are examined to measure the reflectance properties of small and optically immature mare craters that have sampled discrete compositional units the spectral properties of these relatively crystalline mare materials are compared to associated mature soils to determine the effects of space weathering on specific basalt types space weathering is observed to alter the optical properties of distinct lunar basalt units in a systematic manner allowing compositional distinctions to be recognized across maturity states ultraviolet visible reflectance properties of mare basalts are sensitive to titanium content but are relatively independent of maturity state and demonstrate only a slight reddening as regoliths mature to soils other compositional distinctions between basalt types are identified by differences in albedo and band strength of ferrous minerals that are maintained over a full range of maturity states immature deposits within large craters are compared to the spectral properties of well defined mare units to examine the composition of buried materials when craters excavate through the mare highland contamination is readily identified as a mixing relation between mafic and feldspathic lithologies the approach presented here provides new information on the composition and stratigraphy of several nearside mare deposits including the identification of thin low iron and very low titanium basalts in lacus somniorum and more iron rich low titanium basalts in eastern mare frigoris

galileo multispectral imaging of the north polar and eastern limb regions of the moon multispectral images obtained during the galileo probe s second encounter with the moon reveal the compositional nature of the north polar regions and the northeastern limb mare deposits in these regions are found to be primarily low to medium titanium lavas and as on the western limb show only slight spectral heterogeneity the northern light plains are found to have the spectral characteristics of highlands materials show little evidence for the presence of cryptomaria and were most likely emplaced by impact processes regardless of their age

sea ice and marine climate variability for nw iceland denmark strait over the last 2000 cal yr bp md99 2263 is a 46 cm box core collected from djupall a trough that cuts across the nw iceland shelf and ends above denmark strait we provide a multiproxy record that documents changes in the regional marine climate over the last 1700 yr the depth age model is based on seven calibrated radiocarbon dates on mollusk shells and on 210pb and 137cs sediment accumulation rates were variable 0 2 0 8 mm yr but increased dramatically ad 1500 grain size magnetic properties quantitative mineral composition of the 2 mm sediment fraction benthic foraminiferal composition benthic and planktic 18o ratios and abundances fluxes of the sea ice biomarker ip25 were determined to better compare the various proxies 12 of the critical climate proxies were co ordinated into 100 yr sample time series which were examined by principal component analysis the 1st axis explained 49 of the variance and the 2nd axis explained an additional 17 the variables most strongly associated with the 1st axis were sediment pr

lunar mare deposits associated with the orientale impact basin new insights into mineralogy history mode of emplacement and relation to orientale basin evolution from moon mineralogy mapper m3 data from chandrayaan 1 1 moon mineralogy mapper m3 image and spectral reflectance data are combined to analyze mare basalt units in and adjacent to the orientale multiring impact basin models are assessed for the relationships between basin formation and mare basalt emplacement mare basalt emplacement on the western nearside limb began prior to the orientale event as evidenced by the presence of cryptomaria the earliest post orientale event mare basalt emplacement occurred in the center of the basin mare orientale and postdated the formation of the orientale basin by about 60 100 ma over the next several hundred million years basalt patches were emplaced first along the base of the outer rook ring lacus veris and then along the base of the cordillera ring lacus autumni with some overlap in ages the latest basalt patches are as young as some of the youngest basalt deposits on the lunar nearside m3 data show several previously undetected mare patches on the southwestern margins of the basin interior regardless the previously documented increase in mare abundance from the southwest toward the northeast is still prominent we attribute this to crustal and lithospheric trends moving from the farside to the nearside with correspondingly shallower density and thermal barriers to basaltic magma ascent and eruption toward the nearside the wide range of model ages for orientale mare deposits 3 70 1 66 ga mirrors the range of nearside mare ages indicating that the small amount of mare fill in orientale is not due to early cessation of mare emplacement but rather to limited volumes of extrusion for each phase during the entire period of nearside mare basalt volcanism this suggests that nearside and farside source regions may be similar but that other factors such as thermal and crustal thickness barriers to magma ascent and eruption may be determining the abundance of surface deposits on the limbs and farside the sequence timing and elevation of mare basalt deposits suggest that regional basin related stresses exerted control on their distribution our analysis clearly shows that orientale serves as an excellent example of the early stages of the filling of impact basins with mare basalt

cratering history and lunar chronology the moon is exceptional and important because it is the only planetary body besides the earth for which we have both a detailed stratigraphic history and datable rock samples that can be related to specific geomorphologic units fig 5 1 the moon has preserved much of its magmatic and impact record of at least the last 4 billion years while its endogenic history is of great interest for the fundamentals of planetary interiors and surfaces the moon has become a calibration plate for the cratering record of the earth moon system and by extrapolation of the entire inner solar system if one assumes a heliocentric origin for impactor populations these populations range from asteroids through long and short period comets to interplanetary dust and cover a size range from hundreds of kilometers to micrometers figure 5 1 telescopic view of the nearside of the earth s moon with landing sites of the apollo and luna missions this chapter reviews the presently available data sets in support of this paradigmatic assumption as follows 1 the phenomenology of lunar impact craters 2 the terrestrial record of the impact cratering process and the interpretation of terrestrial impactites as far as this ground truth is relevant for the interpretation of lunar impact craters and datable lunar impact breccias and melt rocks 3 the theory and numerical simulation of the cratering process and the characteristics of the earth moon crossing population of impactors asteroids and comets 4 the principles of relative age dating of lunar surface units and the general lunar stratigraphy 5 the stratigraphic significance and ages of lunar samples impactites and basalts and based on this data set the absolute ages of lunar surface units 6 the cratering rate of the moon as a function of time and 7 the time calibration of this cratering rate based on the

lunar impact basins new data for the western limb and far side orientale and south pole aitken basins from the first galileo flyby compositional aspects of impact basin materials can be analyzed using multispectral image data acquired by the galileo solid state imaging ssi experiment during the december 1990 lunar encounter these data provide important information on the spectral properties of the western lunar limb and parts of the far side the ssi images cover the wavelength range 0 4 1 0 m allowing measurement of spectral slope and estimation of the strength of the 1 m absorption due to iron in the mafic minerals olivine and pyroxene among deposits of the 930 km diameter orientale basin exterior ejecta comprising the hevelius formation is relatively homogeneous and spectrally similar to mature apollo 16 soils suggesting an upper crustal source the centrally located maunder formation is distinct from the younger mare basalts but comparable to the hevelius formation in its spectral reflectance properties supporting an interpretation as basin impact melt the montes rook formation located in an annulus between the maunder and the hevelius shows a slightly stronger mafic absorption and may be the deepest crustal material excavated the distal orientale deposits show local mafic enhancements in the schiller schickard and mendel rydberg regions interpreted to represent pre orientale mare deposits or cryptomaria intermixed with overlying basin ejecta in this case maria of sizes comparable to those presently observed were widespread in this region before the orientale impact mixing model analyses are consistent with the ballistic erosion and sedimentation model for ejecta emplacement in the distal regions beyond the continuous ejecta deposit on the southern lunar farside a huge area with an enhanced mafic absorption corresponds to the interior and rim of the pre nectarian south pole aitken impact basin 2000 2500 km in diameter the anomaly is interpreted to be due to several factors including excavation into the more mafic lower crust and the presence of extensive early volcanic fill cryptomare similar to that seen in ancient basins such as smythii and australe these results show that although basin forming events are an important factor in producing lateral heterogeneities in crustal composition and in modifying preexisting deposits such as cryptomaria the majority of material in even the largest basins was excavated from crustal levels our results suggest a gradational vertical crustal stratigraphy consisting of an uppermost mixed crustal layer of anorthosite basin ejecta and cryptomaria deposits generally corresponding to the megaregolith an upper crustal layer of anorthosite and a lower more noritic layer many of the basic questions remaining from this study could be addressed by global high resolution geochemical and mineralogical data obtained by polar orbiting spacecraft

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

nonlinear spectral mixture modeling of lunar multispectral data implications for lateral transport linear and nonlinear spectral mixture models applied to clementine multispectral images of the moon result in roughly similar spatial distributions of end member abundances however there are important differences in the absolute values of the predicted abundances the magnitude of these differences and the implications for understanding geological processes are investigated across a geologic contact between mare and highland in the grimaldi basin on the western nearside of the moon vertical and lateral mass transport due to impact cratering has redistributed mare and highland materials across the contract creating a gradient in composition solutions to linear and nonlinear spectral mixture models for identical spectral end members of mature mare mature highland and fresh crater materials are compared across this simple geologic contact in the grimaldi basin formal estimates of uncertainty in the calculated fractions of the end members are 1 profiles of mare abundance across the contact are extracted and compared quantitatively profiles from the linear mixture models indicate that the geologic contact has an average mare abundance of 60 and the compositional boundary is asymmetric with more mare transported onto the highland side of the contact than highland onto the mare side of the contact in contrast the nonlinear abundance profiles indicate that the geologic contact has an average mare abundance of 50 and the compositional boundary is remarkably symmetric given the expectation that materials will be intimately mixed on the surface of the moon and that the asymmetries implied by the linear model are not consistent with our understanding of lunar surface processes the non linear spectral mixture model is preferred and should be applied whenever quantitative abundance information is required the remarkable symmetry in the compositional gradients across this contact indicates that lateral mass transport dominates over vertical transport at this boundary

striking similarities in temporal changes to spring sea ice occurrence across the central canadian arctic archipelago over the last 7000 years abstract a 7000 year spring sea ice record for victoria strait arc 4 and dease strait arc 5 in the canadian arctic archipelago caa has been determined by quantification of the sea ice diatom derived biomarker ip 25 in two marine sediment piston cores obtained in 2005 the chronologies of the arc 4 and arc 5 cores were determined using a combination of 14 c ams dates obtained from macrobenthic fossils and magnetic susceptibility measurements the ages of the tops of the piston cores were estimated by matching chemical and physical parameters with those obtained from corresponding box cores these analyses revealed that while the top of the arc 4 piston core was estimated to be essentially modern ca 60 cal yr bp a few hundred years of sediment appeared to be absent from the arc 5 piston core downcore changes to ip 25 fluxes for both cores were interpreted in terms of variations in spring sea ice occurrence and correlations between the individual ip 25 flux profiles for victoria strait dease strait and barrow strait reported previously were shown to be statistically significant at both 50 and 100 year resolutions the ip 25 data indicate lower spring sea ice occurrences during the early part of the record ca 7 0 3 0 cal kyr bp and for parts of the late holocene ca 1 5 0 8 cal kyr bp especially for the two lower latitude study locations in contrast higher spring sea ice occurrences existed during ca 3 0 1 5 cal kyr bp and after ca 800 cal yr bp the observation of consecutively lower and higher spring sea ice occurrence during two periods of the late holocene coincides broadly with the medieval warm period and little ice age epochs respectively the ip 25 data are complemented by particle size and mineralogical data although these may alternatively reflect changes in sea level at the study sites the ip 25 data are also compared to previous proxy based determinations of palaeo sea ice and palaeoclimate for the caa including those based on bowhead whale remains and dinocyst assemblages the spatial consistency in the proxy data which most notably indicates an increase in spring sea ice occurrence around 3 cal kyr bp provides a potentially useful benchmark for the termination of the holocene thermal maximum for the central caa

galileo imaging observations of lunar maria and related deposits the galileo spacecraft imaged parts of the western limb and far side of the moon in december 1990 ratios of 0 41 0 56 gin filter images from the solid state hnaging ssi experiment provided information on the titanium content of mare deposits ratios of the 0 76 0 99 gm images indicated 1 gin absorptions associated with fe 2 in mafic minerals mare ages were derived froin crater statistics obtained from lunar orbiter images results on mare coinpositions in western oceanus procellarum and the humorurn basin are consistent with previous earth based observations thus providing confidence in the use of galileo data to extract compositional information mare units in the grimaldi and riccioli basins range in age froin 3 25 to 3 48 ga and consist of medium to medium high titanium 4 to 7 tio2 content lavas the schiller zucchius basin shows a higher 0 76 0 99 gm ratio than the surrounding highlands indicating a potentially higher mafic mineral content consistent with previous interpretations that the area includes mare deposits blanketed by highland ejecta and light plains materials the oldest mare materials in the orientale basin occur in south central mare orientale and are 3 7 ga old youngest mare materials are in lacus autumni and are 2 85 ga old these units are medium to medium high titanium 4 to 7 tio2 basalts thus volcanism was active in orientale for 0 85 ca but lavas were relatively constant in composition galileo data suggest that mendel rydberg mare is similar to mare orientale cryptomare are present as well thus the mare lavas on the western limb and far side to 178oe are remarkably uniform in coinposition being generally of medium to medium high titanium content and having relatively low 0 76 0 99 gin ratios this region of the moon is between two postulated large impact structures the procellarum and the south pole aitken basins and may have a relatively thick crust in areas underlain by an inferred thinner crust i e zones within large basins as at apollo titanium content is often higher however no mare deposits with titanium abundances approaching those of the high titanium 9 to 14 tio2 apollo 11 and 17 basalts nor of the high titanium regions of central oceanus procellarum are seen on the western limb or eastern far side light plains deposits are generally indistinct froin the surrounding highlands in the ssi data and are inferred to be derived primarily from the same material that forins the highlands some of the light plains are too young to be related to basin forming impacts suggesting possible volcanic origin dark mantle deposit compositions derived from ssi data are consistent with earth based observations of similar near side deposits and are interpreted to be pyroclastic materials however the modernitc albedo and 1 gin absorption of the dark mantle deposit on the southwest margin of the orientale basin suggest it is a local pyroclastic deposit contaminated with underlying highland materials from the orientale impact

particle transport processes at slope environments event driven flux across the barents sea continental margin abstract recent studies of the vertical flux of organic matter into the deep ocean have prompted the search for key organic compounds biomarkers as tracers for its production flux and burial into the sediment particulate matter was collected with sediment traps moored at the barents sea continental margin 75 11 78 n 12 29 21 e water depth 2050 m at 610 1840 and 1950 m depth the compositions of the organic material in the two bottoms near traps differ significantly this difference cannot be the result of a change of the vertical sedimentation alone a combination of biomarker analyses quantitative microscopy and bulk parameter determinations on water and sediment trap samples is used in this study to demonstrate that a turbidity plume event at the shelf edge is a vehicle to transport organic and lithogenic particles at high velocities to the benthos of the lower continental margin it is suggested that fine particles were advected into the trap at 1850 m whereas the coarser fraction of higher settling velocities passing several resuspension loops entered the lower trap