imprint of the rheasilvia impact on vesta geologic mapping of quadrangles gegania and lucaria abstract we produced two 1 250 000 scale geologic maps of the adjacent quadrangles av 6 gegania and av 7 lucaria located in the equatorial region of 4 vesta 0 144 e 22 s to 22 n the mapping is based on clear and color filter images of the framing camera fc onboard the dawn spacecraft which has captured the entire illuminated surface of vesta with high spatial resolution up to 20 m pixel and on a digital terrain model derived from fc imagery besides the geologic mapping itself a secondary purpose of this work is to investigate one of the most prominent morphological features on vesta namely the aggregation of several giant equatorial troughs termed the divalia fossae most probably formed during the rheasilvia impact near vesta s south pole the up to 465 km long and 22 km wide troughs show height differences of up to 5 km between adjacent troughs and ridges another imprint of the rheasilvia impact is the 350 km long and 250 km wide swath of ejecta crossing quadrangle av 6 gegania this lobe shows a distinct appearance in fc color ratios and a high albedo in fc images indicating a mineralogical similarity to material typically found within the rheasilvia basin in particular composed of diogenite rich howardites almost the entire northern half of the mapping area shows the oldest surface being dominated by upper crustal basaltic material to the south increasingly younger formations related to the rheasilvia impact occur either indicated by the troughs formed by rheasilvia or by the rheasilvia ejecta itself only medium sized impact craters with diameters less than 22 km occur within the two mapped quadrangles some of the craters exhibit ejecta blankets and or distinctly dark or bright ejecta material in ejecta rays outside and exposures within the crater and mass wasting deposits down crater slopes forming the youngest surfaces

the unique geomorphology and physical properties of the vestalia terra plateau abstract we produced a geologic map of the av 9 numisia quadrangle of asteroid vesta using dawn spacecraft data to serve as a tool to understand the geologic relations of surface features in this region these features include the plateau vestalia terra a hill named brumalia tholus and an unusual dark ribbon material crossing the majority of the map area stratigraphic relations suggest that vestalia terra is one of the oldest features on vesta despite a model crater age date similar to that of much of the surface of the asteroid cornelia numisia and drusilla craters reveal bright and dark material in their walls and both cornelia and numisia have smooth and pitted terrains on their floors suggestive of the release of volatiles during or shortly after the impacts that formed these craters cornelia fabia and teia craters have extensive bright ejecta lobes while diogenitic material has been identified in association with the bright teia and fabia ejecta hydroxyl has been detected in the dark material within cornelia numisia and drusilla three large pit crater chains appear in the map area with an orientation similar to the equatorial troughs that cut the majority of vesta analysis of these features has led to several interpretations of the geological history of the region vestalia terra appears to be mechanically stronger than the rest of vesta brumalia tholus may be the surface representation of a dike fed laccolith the dark ribbon feature is proposed to represent a long runout ejecta flow from drusilla crater

holocene alluvial sediment storage in a small river catchment in the loess area of central belgium abstract soil erosion and sediment deposition widely affect landscape development particularly in erosion prone areas with loess derived soils nevertheless until now few attempts were made to quantify soil losses and sediment storage over long centennial or millennial timescales in this study the holocene alluvial sediment storage in a small river catchment 52 km2 of the belgian loess belt is estimated and a preliminary sediment budget for the catchment is presented in the valley of the nethen river c 13 km long a detailed survey of the alluvial sediment archive was conducted hand augerings and percussion drillings were made along cross valley transects at 12 locations in the catchment ams 14c dating of peat samples provided a temporal framework for the interpretation of the cores results show that the thickness of holocene sediment deposits in the nethen valley is 4 to 6 m which corresponds to a total clastic sediment mass of 14 106 t stored in the valley bottom three alluvial units could be distinguished and associated with deposition phases from 9600 to 2900 b c 2900 b c to a d 1000 and a d 1000 to present in contrast to the older sediments units 1 and 2 deposits from the last 1000 year unit 3 contain little organic matter they are seldom intercalated with peat layers and devoid of tufa unit 3 reaches a thickness of c 2 m thereby representing 50 of the holocene sediment mass stored in the alluvial plain the mean sedimentation rate in the alluvial plain for this last phase is 26 t ha 1 a 1 which is about tenfold larger than the sedimentation rates calculated for the older holocene sediment units sediment supply towards the alluvial plain has therefore increased tremendously since medieval times these results are in contrast to dating results obtained for colluvial sediments in a nearby dry valley within the catchment of the nethen where soil erosion and sediment deposition started in the early iron age and was already substantial during the roman age this means that there is a time lag of about one millennium between the onset of high sedimentation rates in the upstream area and high deposition rates in the alluvial plain this is probably caused by a change in coupling sediment connectivity between the plateau slopes and rivers as soil erosion proceeds first the dry zero order valleys in the catchment act as sediment traps and only after these are filled sediment reaches the floodplains the preliminary sediment budget for the nethen catchment illustrates that 50 of the sediment that was eroded during the holocene was stored in colluvial deposits which are mainly located on footslopes and in dry valley bottoms another 29 of the sediment mass is stored in the alluvial plain

the impact of wallachian settlement on relief and alluvia composition in small valleys of the carpathian mts czech republic abstract the impact of the wallachian settlement on small mountain catchments has been studied at the example of skor ansk and hartisov streams moravskoslezske beskydy mts western outer carpathians between the 16th and the 19th centuries the wallachian people introduced pastoral management originating from the woodless balkans to the forested mid altitude mountain area under study this area was subjected to rapid settlement intense grazing in forests and slash and burn deforestation to assess the geomorphic effects of wallachian activity in the catchments studied grain size structure organic matter content and the plant macrofossil composition of the alluvia forming terrace levels in the mouths of the skor ansk and hartisov streams were analysed radiocarbon dating 137 cs and 210 pb analyses and dendrochronological dating were also applied to determine the age of the alluvia studied the results were compared with land use and land cover changes recorded on archival maps and pictures and with population changes in the study area it was found that the two successive trends of catchment settlement and later depopulation have led to the development of inset terraces on the outlet fans of the skor ansk and hartisov streams in the study catchments both settlement deforestation and depopulation land abandonment occurred very rapidly which also caused abrupt geomorphic changes before human disturbance fluvial erosion and the redeposition of older pleistocene deposits predominated as a result coarse gravel alluvia were deposited within stream channels the stage of massive overbank accumulation of fine grained alluvia was a reflection of intensified delivery of slope material into valley floors from catchments deforested by the wallachians the later stage of vertical incision of channels resulted from the decrease of sediment supply from hillslopes to river channels during catchment depopulation and afforestation

the geological nature of dark material on vesta and implications for the subsurface structure abstract deposits of dark material appear on vesta s surface as features of relatively low albedo in the visible wavelength range of dawn s camera and spectrometer mixed with the regolith and partially excavated by younger impacts the material is exposed as individual layered outcrops in crater walls or ejecta patches having been uncovered and broken up by the impact dark fans on crater walls and dark deposits on crater floors are the result of gravity driven mass wasting triggered by steep slopes and impact seismicity the fact that dark material is mixed with impact ejecta indicates that it has been processed together with the ejected material some small craters display continuous dark ejecta similar to lunar dark halo impact craters indicating that the impact excavated the material from beneath a higher albedo surface the asymmetric distribution of dark material in impact craters and ejecta suggests non continuous distribution in the local subsurface some positive relief dark edifices appear to be impact sculpted hills with dark material distributed over the hill slopes dark features inside and outside of craters are in some places arranged as linear outcrops along scarps or as dark streaks perpendicular to the local topography the spectral characteristics of the dark material resemble that of vesta s regolith dark material is distributed unevenly across vesta s surface with clusters of all types of dark material exposures on a local scale some craters expose or are associated with dark material while others in the immediate vicinity do not show evidence for dark material while the variety of surface exposures of dark material and their different geological correlations with surface features as well as their uneven distribution indicate a globally inhomogeneous distribution in the subsurface the dark material seems to be correlated with the rim and ejecta of the older veneneia south polar basin structure the origin of the dark material is still being debated however the geological analysis suggests that it is exogenic from carbon rich low velocity impactors rather than endogenic from freshly exposed mafic material or melt exposed or created by impacts

geologic mapping of ejecta deposits in oppia quadrangle asteroid 4 vesta abstract oppia quadrangle av 10 288 360 e 22 is a junction of key geologic features that preserve a rough history of asteroid 4 vesta and serves as a case study of using geologic mapping to define a relative geologic timescale clear filter images stereo derived topography slope maps and multispectral color ratio images from the framing camera on nasa s dawn spacecraft served as basemaps to create a geologic map and investigate the spatial and temporal relationships of the local stratigraphy geologic mapping reveals the oldest map unit within av 10 is the cratered highlands terrain which possibly represents original crustal material on vesta that was then excavated by one or more impacts to form the basin feralia planitia saturnalia fossae and divalia fossae ridge and trough terrains intersect the wall of feralia planitia indicating that this impact basin is older than both the veneneia and rheasilvia impact structures representing pre veneneian crustal material two of the youngest geologic features in av 10 are lepida 45 km diameter and oppia 40 km diameter impact craters that formed on the northern and southern wall of feralia planitia and each cross cuts a trough terrain the ejecta blanket of oppia is mapped as dark mantle material because it appears dark orange in the framing camera clementine type color ratio image and has a diffuse gradational contact distributed to the south across the rim of rheasilvia mapping of surface material that appears light orange in color in the framing camera clementine type color ratio image as light mantle material supports previous interpretations of an impact ejecta origin some light mantle deposits are easily traced to nearby source craters but other deposits may represent distal ejecta deposits emplaced 5 crater radii away in a microgravity environment

spectral analysis of the quadrangles av 13 and av 14 on vesta abstract the av 13 tuccia and av 14 urbinia quadrangles are located in the south west region of vesta they are characterized by a large topographic variability from the highest vestalia terra highlands to the lowest rheasilvia basin many geological units in these quadrangles are not associated with mineralogical variability as shown by the color composite maps maps of mafic absorption band center position reveal that the principal lithology is eucrite rich howardite but diogenite rich howardite areas are also present corresponding to particular features such as antonia and justina craters which are characterized by strong mafic absorptions these quadrangles especially urbinia contain many bright ejecta such as those of tuccia crater which are the highest reflectance materials on vesta zambon et al 2014 dark areas are present and correspond to regions with deeper oh signature the two quadrangles contain many vertical ridge crests associated with the rheasilvia impact these ridges do not show mineralogical differences with respect to their surroundings but have a distinctive appearance in color ratio composite images

40ar 39ar dating of apollo 12 regolith implications for the age of copernicus and the source of nonmare materials abstract twenty one 2 4 mm rock samples from the apollo 12 regolith were analyzed by the 40 ar 39 ar geochronological technique in order to further constrain the age and source of nonmare materials at the apollo 12 site among the samples analyzed are 2 felsites 11 kreep breccias 4 mare basalt bearing kreep breccias 2 alkali anorthosites 1 olivine bearing impact melt breccia and 1 high th mare basalt most samples show some degree of degassing at 700 800 ma with minimum formation ages that range from 1 0 to 3 1 ga we estimate that this degassing event occurred at 782 21 ma and may have been caused by the copernicus impact event either by providing degassed material or by causing heating at the apollo 12 site 40 ar 39 ar dating of two alkali anorthosite clasts yielded ages of 3 256 0 022 ga and 3 107 0 058 ga we interpret these ages as the crystallization age of the rock and they represent the youngest age so far determined for a lunar anorthosite the origin of these alkali anorthosite fragments is probably related to differentiation of shallow intrusives later impacts could have dispersed this material by lateral mixing or vertical mixing

eucritic crust remnants and the effect of in falling hydrous carbonaceous chondrites characterizing the composition of vesta s marcia region abstract the equatorial marcia quadrangle region is characterized by the large relatively young impact craters marcia and calpurnia and their surrounding dark ejecta field a hill with a dark rayed crater named aricia tholus and an unusual diffuse material surrounding the impact crater octavia the spectral analysis indicates that while this region is relatively uniform in the pyroxene band centers it instead shows large differences in pyroxene band depths and reflectance a large variation of reflectance is seen in the quadrangle bright and dark materials are present as diffuse material and as concentrated spots and outcrops moreover oh signature is pervasive in the quadrangle with a few exceptions the region especially the marcia ejecta field is characterized by spectra showing the 2 m band shifted at long wavelengths this is commonly associated with eucritic material believed to have crystallized as lava on vesta s surface or within relatively shallow level dikes and plutons thus suggesting that this region is a remnant of the old vestan basaltic crust however other characteristics of the spectra do not fully fit the eucritic composition indicating an alternative explanation for the band center distribution including the presence of carbonaceous chondritic material mixed with the native vestan pyroxene the detailed mineralogical analysis of the marcia quadrangle indicates that this quadrangle is the result of the mixture of the vestan endogenic minerals with the exogenic carbonaceous chondrites the stratigraphic units around marcia clearly show the bright uncontaminated material interlaced and mixed with the dark material that contains a strong oh signature only few small areas can be considered as representative of the old vestan original material

asynchronous holocene colluvial and alluvial aggradation a matter of hydrosedimentary connectivity based on optically stimulated luminescence osl and radiocarbon dating we establish chronologies of colluviation and alluviation in different floodplain sections of the northwestern wetterau loess basin germany similar to some other european valley floors holocene floodplain aggradation is marked by two important breaks 1 a millennial scale delay between the neolithic agricultural colluviation and floodplain aggradation in loess catchments agricultural colluviation started at about 7000 cal bp and anthropogenic floodplain aggradation only at about 2200 200 cal bp 2 a centennial scale variability in a temporary rise in rates of anthropogenic floodplain aggradation up to 3 6 1 7 mm yr during the high middle ages in directly neighbouring reaches independent archaeologic historic and vegetation records document distinct agricultural histories of hillsides and floodplains and highlight the importance of hydrosedimentary connectivity as compared with land use intensity the late iron age

surface lithologic heterogeneity of asteroid 4 vesta abstract high precision spectrophotometry of 4 vesta the third largest asteroid was used to establish the surface composition of this body and to investigate mineralogical variations across its surface the average surface of vesta is analogous to howardite and or polymict eucrite assemblages regolith derived members of the hed meteorite suite which consist of a eucrite matrix containing differing amounts of a diogenite component color and or spectral changes which exhibit a consistent relationship to rotational phasing are evident in 16 of 18 studies of vesta dating back to 1929 including the present work after elimination of possible sources of spurious spectral or color changes it is concluded that these variations arise from hemispheric variations in surface materials and hence provide a means of spatially resolving subhemispheric compositional units on the surface of vesta the background surface of vesta is a relatively dark howardite or polymict eucrite pyroxene plagioclase assemblage with several compositionally distinct bright regions clustered in one hemisphere viewed around the maximum in vesta s lightcurve these include what appears to be an olivine bearing unit suggested name leslie formation located near vesta s equator which probably represents an impact basin and or its associated ejecta that penetrated through the basaltic crust other high albedo compositional units including an apparently low calcium eucrite region and several diogenite pyroxenite regions at least one located near the southern pole may be smaller shallower impact basins by analogy to the eucrite meteorites which represent surface flows or shallow intrusions and which constitute the major component of the regolith derived howardites and polymict eucrites we conclude that the howardite polymict eucrite units represent a regolith gardened original surface of vesta it is probable that the low albedo of the background surface on vesta is due to an age related darkening effect similar to that inferred from the galileo images of gaspra and ida this mechanism is consistent with the correlation of absorption feature intensity with the lightcurve vesta appears to have an old eucritic surface darkened with age and represented among the meteorites by the regolith derived howardites and polymict eucrites on which several impacts on one hemisphere have exposed fresher brighter diogenite and olivine bearing material based on qualitative analysis of the mineralogical variations as a function of rotation a generalized lithologic map of vesta was produced there is reasonable control on the longitude of lithologic features but little control on their latitudes except where specifically noted in producing this map discrete circular features were used on the plausible assumption that impacts have been the most important geologic process on this surface for most of the age of the solar system the shape of the features has thus been assumed rather than derived and is subject to future revision as data improve

dawn completes its mission at 4 vesta the dawn mission was designed to test our hypothesis about the origin and evolution of the early solar system by visiting the largest differentiated basaltic asteroid 4 vesta believed to be a survivor from the earliest times of rocky body formation observations from orbit show that vesta is the parent body of the howardite eucrite diogenite meteorites vesta has an iron core and a eucritic diogenitic crust its surface is characterized by abundant impact craters but with no evident volcanic features it has two ancient impact basins in the southern hemisphere that are associated with circum planetary troughs the northern hemisphere is the more heavily cratered and contains the oldest terrains the surface of vesta is diverse with north south and east west dichotomies in the eucrite to diogenite ratio its surface contains both very bright and very dark material and its color varies strongly from region to region both the mineralogical and the elemental compositions agree with that expected for the hed parent body significant oh or h may be present in the upper crust and the presence of pits in fresh craters is consistent with the devolatilization of the surface after a collision either brought to or tapped a source of water on vesta the presence of dark material on the surface of vesta suggests efficient transport pathways for organic material and the mixing of the dark material with the more pristine pyroxene explains the varying albedo across the surface vesta has proven to be a reliable witness to the formation of the solar system

morphology and formation ages of mid sized post rheasilvia craters geology of quadrangle tuccia vesta abstract a variety of geologic landforms and features are observed within quadrangle av 13 tuccia in the southern hemisphere of vesta the quadrangle covers parts of the highland vestalia terra as well as the floors of the large rheasilvia and veneneia impact basins which results in a substantial elevation difference of more than 40 km between the northern and the southern portions of the quadrangle measurements of crater size frequency distributions within and surrounding the rheasilvia basin indicate that gravity driven mass wasting in the interior of the basin has been important and that the basin has a more ancient formation age than would be expected from the crater density on the basin floor alone subsequent to its formation rheasilvia was superimposed by several mid sized impact craters the most prominent craters are tuccia eusebia vibidia galeria and antonia whose geology and formation ages are investigated in detail in this work these impact structures provide a variety of morphologies indicating different sorts of subsequent impact related or gravity driven mass wasting processes understanding the geologic history of the relatively young craters in the rheasilvia basin is important in order to understand the even more degraded craters in other regions of vesta

pattern and forcing of northern hemisphere glacier variations during the last millennium time series depicting mountain glacier fluctuations in the alps display generally similar patterns over the last two centuries as do chronologies of glacier variations for the same interval from elsewhere in the northern hemisphere episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production as inferred from acidity variations in a greenland ice core advances occur whenever acidity levels rise sharply from background values to reach concentrations 1 2 equiv h kg above background a phase lag of about 10 15 yr equivalent to reported response lags of alpine glacier termini separates the beginning of acidity increases from the beginning of subsequent ice advances a similar relationship but based on limited and less reliable historical data and on lichenometric ages is found for the preceding 2 centuries calibrated radiocarbon dates related to advances of non calving and non surging glaciers during the earlier part of the little ice age display a comparable consistent pattern an interval of reduced acidity values between about 1090 and 1230 a d correlates with a time of inferred glacier contraction during the medieval optimum the observed close relation between noothern hemisphere glacier fluctuations and variations in greenland ice core acidity suggests that sulfur rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations and therefore of climate on a decadal scale the amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of little ice age alacier advances ca 0 5 1 2 c as inferred from depression of equilibrium line altitudes

impact excavation on asteroid 4 vesta hubble space telescope results hubble space telescope images of asteroid 4 vesta obtained during the favorable 1996 apparition show an impact crater 460 kilometers in diameter near the south pole color measurements within the 13 kilometer deep crater are consistent with excavation deep into a high calcium pyroxene rich crust or olivine upper mantle about 1 percent of vesta was excavated by the crater formation event a volume sufficient to account for the family of small vesta like asteroids that extends to dynamical source regions for meteorites this crater may be the site of origin for the howardite eucrite and diogenite classes of basaltic achondrite meteorites

late holocene evolution of the becva river floodplain outer western carpathians czech republic abstract to reconstruct the geomorphic imprint of the anthropogenic and natural environmental changes in the late holocene we studied the alluvial record of the becva river floodplain outer western carpathians czech republic coring geophysical sounding and lithological analysis of floodplain deposits supported by ams accelerator mass spectrometry dating enabled the establishment of the primary evolutionary stages of late holocene floodplain evolution during the late atlantic and early subboreal periods gravel aggradation and braided environments occurred in the studied floodplain the late subboreal and early subatlantic are characterised by overbank sedimentation and the middle subatlantic is marked by the recurrence of gravel aggradation a major incision phase took place during the mediaeval warm period the onset of overbank sedimentation in the 15th century correlated with ongoing deforestation of the lower parts of catchment and colonisation of the mountain ridges during the 16th 17th centuries further accelerated this process during the 20th century reforestation of mountains and river channel training resulted in a significant incision phase our data suggest that climate fluctuations were major driving factors for the morpho sedimentary evolution of the floodplain approximately up to the 12th century whereas in the latter evolution period anthropogenic activity superseded natural factors this transition occurred more than one millennium later than in other central and western european catchments

the geology of the marcia quadrangle of asteroid vesta assessing the effects of large young craters abstract we used dawn spacecraft data to identify and delineate geological units and landforms in the marcia quadrangle of vesta as a means to assess the role of the large relatively young impact craters marcia 63 km diam and calpurnia 53 km diam and their surrounding ejecta field on the local geology we also investigated a local topographic high with a dark rayed crater named aricia tholus and the impact crater octavia that is surrounded by a distinctive diffuse mantle crater counts and stratigraphic relations suggest that marcia is the youngest large crater on vesta in which a putative impact melt on the crater floor ranges in age between 40 and 60 ma depending upon choice of chronology system and marcia s ejecta blanket ranges in age between 120 and 390 ma depending upon choice of chronology system we interpret the geologic units in and around marcia crater to mark a major vestan time stratigraphic event and that the marcia formation is one of the geologically youngest formations on vesta marcia crater reveals pristine bright and dark material in its walls and smooth and pitted terrains on its floor the smooth unit we interpret as evidence of flow of impact melts and for the pitted terrain release of volatiles during or after the impact process the distinctive dark ejecta surrounding craters marcia and calpurnia is enriched in oh or h bearing phases and has a variable morphology suggestive of a complex mixture of impact ejecta and impact melts including dark materials possibly derived from carbonaceous chondrite rich material aricia tholus which was originally interpreted as a putative vestan volcanic edifice based on lower resolution observations appears to be a fragment of an ancient impact basin rim topped by a dark rayed impact crater octavia crater has a cratering model formation age of 280 990 ma based on counts of its ejecta field depending upon choice of chronology system and its ejecta field is the second oldest unit in this quadrangle the relatively young craters and their related ejecta materials in this quadrangle are in stark contrast to the surrounding heavily cratered units that are related to the billion years old or older rheasilvia and veneneia impact basins and vesta s ancient crust preserved on vestalia terra

sedimentary record of early wood burning in alluvium of mountain streams in the bieszczady range polish carpathians abstract the youngest alluvium in the headwater part of the san valley in the bieszczady range polish carpathians is sandy mud lying with a sharp contact on older gravels the mud alluvium contains at its base accumulations of wood debris rich in charcoal radiocarbon dates of the wood debris suggest that the mud alluvium was laid down during the second half of this last millennium the accumulation of the wood debris seems to be related to the fire clearance of forests by early farmers who settled in the area the higher part of the mud alluvium includes dispersed wood debris ash and charcoal whose appearance is related to the activity of small wood processing establishments until the early 20th century

late holocene evolution of a floodplain impounded by the smrduta landslide carpathian mountains czech republic we present here a detailed study of the sedimentary archive within a landslide controlled impounded floodplain smrduta site czech flysch carpathians using geochronological 14c and 137cs sedimentological and pollen evidence a sedimentary sequence deposited above the landslide dam points to three highly discontinuous and instantaneous depositional events dated to 4 6 and 2 0 cal ka bp whereas the last cycle started approximately in the 17 18th centuries and has continued to recent times stages of mass movement activity revealed by the smrduta landslide correlate well with major humid late holocene oscillations suggesting its high sensitivity to century scale climatic deteriorations the character of lithological units forming individual sedimentary pulses erosional hiatuses and sedimentary traces caused by the july 1997 extreme flood indicate a decisive role of large flood events during accretion and erosion of the floodplain impounded section

composition of the northern regions of vesta analyzed by the dawn mission abstract the surface composition of the northern regions of vesta observed by the dawn spacecraft offers the possibility to test several hypotheses related to impact related processes we used mostly imaging spectrometry in the visible and near infrared to assess the distribution of mafic lithologies hydrated components and albedo properties and use the link with howardite eucrite and diogenite meteorites heds to investigate the origin of those materials we established that rheasilvia ejecta reached part of the northern regions and have a diogenitic rich composition characteristic of the lower crust investigations of the antipodes of the two major impact basins rheasilvia and veneneia did not reveal any correlation between geographic location geological features and the surface composition the northern wall of mamilia crater which is one of the freshest craters above 22 n contains relatively pure eucritic rich diogenitic rich and dark hydrated materials which are representative of the rest of the northern regions and most of vesta with the exception of an olivine like component found in bellicia crater by ammannito et al ammannito e et al 2013a nature 504 7478 122 125 we determined that similar types of materials are found in various proportions over a large region including bellicia arruntia and pomponia craters and their origin does not seem to be related to rheasilvia ejecta these materials are hydrated which could indicate an exogenous origin and not as dark as expected for carbonaceous chondrites which likely compose the majority of dark hydrated materials on vesta spectral mixture analysis reveals that mixtures of pyroxenes hypersthene pigeonite and diopside could offer an alternative interpretation to olivine in this area

compositional evidence of magmatic activity on vesta like the earth and other terrestrial planets the asteroid vesta has a basaltic crust and a large iron core its surface is dominated by impact craters of all sizes and has tectonic features the presence of basaltic compositions olivine howardite eucrite diogenite meteorites and models of vesta s formation suggests that volcanic and or magmatic activity could have occurred on vesta a global search for lobate structures did not find unequivocal evidence of volcanic features nevertheless several morphological properties of brumalia tholus on vestalia terra suggest that this topographic high most likely formed as a magmatic intrusion the presence of more orthopyroxene rich material relative to surrounding terrain in the ejecta of teia a fresh impact crater on the northern face of brumalia tholus supports the hypothesis of magmatic intrusions on vesta

spectroscopic characterization of mineralogy and its diversity across vesta the mineralogy of vesta based on data obtained by the dawn spacecraft s visible and infrared spectrometer is consistent with howardite eucrite diogenite meteorites there are considerable regional and local variations across the asteroid spectrally distinct regions include the south polar rheasilvia basin which displays a higher diogenitic component and equatorial regions which show a higher eucritic component the lithologic distribution indicates a deeper diogenitic crust exposed after excavation by the impact that formed rheasilvia and an upper eucritic crust evidence for mineralogical stratigraphic layering is observed on crater walls and in ejecta this is broadly consistent with magma ocean models but spectral variability highlights local variations which suggests that the crust can be a complex assemblage of eucritic basalts and pyroxene cumulates overall vesta mineralogy indicates a complex magmatic evolution that led to a differentiated crust and mantle

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

impact of mediaeval agriculture on the alluvium in the san river headwaters polish eastern carpathians abstract an abrupt change in sedimentary processes occurs in the alluvium of the san river headwaters in the bieszczady mountains polish eastern carpathians older gravels are overlain with a sharp boundary by an extensive cover of sand and silt which is enriched in wood debris partly burned at the base the spatial distribution of the fine grained alluvium the wood debris composition and radiocarbon ages are best explained by a relatively sudden onset of deforestation and cultivation of the valley bottom and slopes in the middle of the second millennium this corresponds well with palynological archaeological and historical data on the agricultural colonisation of the valley

olivine or impact melt nature of the orange material on vesta from dawn abstract nasa s dawn mission observed a great variety of colored terrains on asteroid 4 vesta during its survey with the framing camera fc here we present a detailed study of the orange material on vesta which was first observed in color ratio images obtained by the fc and presents a red spectral slope the orange material deposits can be classified into three types a diffuse ejecta deposited by recent medium size impact craters such as oppia b lobate patches with well defined edges nicknamed pumpkin patches and c ejecta rays from fresh looking impact craters the location of the orange diffuse ejecta from oppia corresponds to the olivine spot nicknamed leslie feature first identified by gaffey gaffey m j 1997 icarus 127 130 157 from ground based spectral observations the distribution of the orange material in the fc mosaic is concentrated on the equatorial region and almost exclusively outside the rheasilvia basin our in depth analysis of the composition of this material uses complementary observations from fc the visible and infrared spectrometer vir and the gamma ray and neutron detector grand several possible options for the composition of the orange material are investigated including cumulate eucrite layer exposed during impact metal delivered by impactor olivine orthopyroxene mixture and impact melt based on our analysis the orange material on vesta is unlikely to be metal or olivine originally proposed by gaffey gaffey m j 1997 icarus 127 130 157 analysis of the elemental composition of oppia ejecta blanket with grand suggests that its orange material has 25 cumulate eucrite component in a howarditic mixture whereas two other craters with orange material in their ejecta octavia and arruntia show no sign of cumulate eucrites morphology and topography of the orange material in oppia and octavia ejecta and orange patches suggests an impact melt origin a majority of the orange patches appear to be related to the formation of the rheasilvia basin combining the interpretations from the topography geomorphology color and spectral parameters and elemental abundances the most probable analog for the orange material on vesta is impact melt

olivine in an unexpected location on vesta s surface although olivine was expected to occur within the deep south pole basins of asteroid vesta which are thought to be excavated mantle rocks spectral data from nasa s dawn spacecraft show that it instead occurs as near surface materials in vesta s northern hemisphere between july 2011 and september 2012 nasa s dawn spacecraft was in orbit around the asteroid vesta in this paper dawn s visible and infrared mapping spectrometer vir team presents a surprising finding the signature of olivine on the asteroid s surface olivine is a major component of the mantle of differentiated bodies including earth vesta is a large asteroid large enough to have differentiated into an earth like layered structure and the expectation was that olivine would be found within vesta s deep south pole basins thought to be excavated mantle rocks yet the spectroscopic data reveal olivine rich material close to the surface in the northern hemisphere an understanding of the differentiation processes that have occurred on vesta will be invaluable as a window on the primordial solar system but these latest findings show that vesta s evolutionary history is more complicated than was thought olivine is a major component of the mantle of differentiated bodies including earth howardite eucrite and diogenite hed meteorites represent regolith basaltic crust lower crust and possibly ultramafic mantle samples of asteroid vesta which is the lone surviving large differentiated basaltic rocky protoplanet in the solar system1 only a few of these meteorites the orthopyroxene rich diogenites contain olivine typically with a concentration of less than 25 per cent by volume2 olivine was tentatively identified on vesta3 4 on the basis of spectral and colour data but other observations did not confirm its presence5 here we report that olivine is indeed present locally on vesta s surface but that unexpectedly it has not been found within the deep south pole basins which are thought to be excavated mantle rocks6 7 8 instead it occurs as near surface materials in the northern hemisphere unlike the meteorites the olivine rich more than 50 per cent by volume material is not associated with diogenite but seems to be mixed with howardite the most common7 9 surface material olivine is exposed in crater walls and in ejecta scattered diffusely over a broad area the size of the olivine exposures and the absence of associated diogenite favour a mantle source but the exposures are located far from the deep impact basins the amount and distribution of observed olivine rich material suggest a complex evolutionary history for vesta

mineralogical analysis of the oppia quadrangle of asteroid 4 vesta evidence for occurrence of moderate reflectance hydrated minerals abstract quadrangle av 10 oppia is one of five quadrangles that cover the equatorial region of asteroid 4 vesta this quadrangle is notable for the broad spectrally distinct ejecta that extend south of the oppia crater these ejecta exhibit the steepest reddest visible spectral slope observed across the asteroid and have distinct color properties as seen in multispectral composite images compared to previous works that focused on the composition and nature of unusual orange ejecta found on vesta here we take into account a broader area that includes several features of interest with an emphasis on mineralogy as inferred from data obtained by dawn s visible infrared mapping spectrometer vir our analysis shows that the older northern and northeastern part of av 10 is dominated by howardite like material while the younger southwestern part including oppia and its ejecta blanket has a markedly eucritic mineralogy the association of the mineralogical information with the geologic and topographic contexts allows for the establishment of relationships between the age of the main formations observed in this quadrangle and their composition a major point of interest in the oppia quadrangle is the spectral signature of hydrous material seen at the local scale this material can be mapped by using high resolution vir data combined with multispectral image products from the dawn framing camera fc so as to enable a clear correlation with specific geologic features hydrated mineral phases studied previously on vesta generally correlate with low albedo material delivered by carbonaceous asteroids however our analysis shows that the strongest oh signature in av 10 is found in a unit west of oppia previously mapped as light mantle material and showing moderate reflectance and a red visible slope with the available data we cannot yet assess the presence of water in this material however we offer a possible explanation for its origin

the contamination of the surface of vesta by impacts and the delivery of the dark material abstract the dawn spacecraft recently observed the presence of dark material which in turn proved to be associated with the presence of oh and h rich material on the surface of vesta the source of this dark material has been almost unanimously identified with the low albedo asteroids likely analogous to the carbonaceous chondrites found on earth that impacted on vesta over its lifetime however it is still a matter of debate whether the delivery of the dark material is associated with a few large impact events to micrometeorites or to the continuous secular flux of impactors on vesta the continuous flux scenario in particular predicts that a significant fraction of the exogenous material accreted by vesta should be due to non dark impactors likely analogous to ordinary chondrites which instead represent only a minor contaminant in the howardite eucrite diogenite meteorites in this work we explored the continuous flux scenario and its implications for the composition of the vestan regolith taking advantage of the data from the dawn mission and the howardite eucrite diogenite meteorites to constrain the contamination history of vesta we developed a model for the delivery of the exogenous material to vesta and verified how the results it supplies are sensitive to the different parameters we consider we calibrated the flux of impactors predicted by our model with the number of dark craters observed inside the rheasilvia basin and we tested the assumptions on the impact conditions by studying the formation of cornelia crater and of its dark deposits with a hydrocode simulation we used our calibrated model to show that the stochastic events scenario and the micrometeoritic flux scenario are just natural consequences of the continuous flux scenario we then used the model to estimate the amounts of dark and hydroxylate materials that were delivered on vesta since the late heavy bombardment and we showed how our results match well with the values estimated by the dawn mission we finally used our model to assess the amount of fe and siderophile elements that the continuous flux of impactors would mix in the vestan regolith concerning the siderophile elements we focused our attention on the role of ni the results we obtained are in agreement with the data available on the fe and ni content of the howardite eucrite diogenite meteorites and can be used as a reference frame in future studies of the data from the dawn mission and of the howardite eucrite diogenite meteorites our model cannot yet provide an answer to the conundrum of the fate of the missing non carbonaceous contaminants but we discuss some possible reasons for this discrepancy with the otherwise coherent picture described by our results

last glacial interglacial cycle in the evolution of river valleys in southern and central poland abstract the last glacial interglacial cycle is represented usually by several cuts and fills which have formed 2 3 terrace steps from the last cold stage and by two or more fills of lateglacial holocene age their number depends on the size of the river valley and the position in the longitudinal profile the sequence of changes reflects shorter stadial interstadial climatic fluctuations generally aggradation dominates during the cooler phases of the vistulian and during the interpleniglacial the most distinct erosional phases occurred during the change from a more oceanic to a more continental climate before the maximum extension of the ice sheet 25 20 ka bp and during the upper pleniglacial lateglacial transition 15 13 ka bp the second phase coincides with the rapid downcutting in the lower course of the main vistula valley which had been blocked earlier by the scandinavian ice sheet in the holocene aggradation prevailed accelerated by anthropogenic soil erosion it was only in the mountain foreland that shorter lived hydrological changes resulted in well expressed several cuts and fills

the spectral parameter maps of vesta from vir data abstract here we present the spectral parameter maps used in this surface composition of vesta special issue the use of spectral parameters have been important since the first ground based observations of vesta as they can describe single mineralogic aspects as abundances or change in surface composition mapping these parameters over the surface shows the mineralogic diversity across the asteroid vesta in this work we discuss the development of the maps which are produced from the data of the visible and infrared mapping spectrometer onboard nasa s dawn mission we describe how we processed the vir spectra and how we produced the geometries of data acquisition spectra and geometries are used to design a geographic information system procedure to mosaic these data we conclude the article with a description of the trends of the pyroxene related spectral parameters across the asteroid and some statistics on the spectral parameters of each map within the quadrangle based scheme used in this special issue

detections and geologic context of local enrichments in olivine on vesta with vir dawn data the magmatism characterizing the early history of the asteroid vesta has long been investigated with the mafic and ultramafic meteorites howardite eucrite and diogenite hed the lack of geologic context for the meteorites however has limited its understanding here we use the visible to near ir vir orbital observations of vesta s surface to detect relative enrichments in olivine and to study the associated geologic features because the near ir signature of olivine on vesta s surface is subtle relative to the widespread pyroxene absorption bands a method was developed to distinguish olivine enrichments from admixture of pyroxenes with high fe2 m1 dark material and potential fe bearing glass relative enrichment of olivine 50 60 vol is found in 2 5 km wide morphologically fresh areas our global survey reveals a dozen of these areas clustering in the eastern hemisphere of vesta the hemispherical coincidence with a widespread low enrichment in diogenite like pyroxene suggests the presence of a distinct compositional terrain on the central mound of the rheasilvia impact basin no olivine enrichment was found suggesting the absence of an olivine dominated mantle above the basin s excavation depth or alternatively a low amount of olivine homogeneously mixed with diogenite like pyroxenes rare olivine enriched areas in close proximity to diogenite like pyroxene are found as part of material ejected by the rheasilvia impact such cooccurrence is reminiscent of local ultramafic lithologies within the crust the possible formation of such lithologies on vesta is supported by some hed meteorites dominated by olivine and orthopyroxene

alluvial fans as an effect of long term man landscape interactions and moist climatic conditions a case study from the glubczyce plateau sw poland abstract at the mouth of periodically drained valleys in the loess glubczyce plateau sw poland favorable conditions for deposition of alluvial fan sediments occur so these forms are very common in the investigated area the origin of the forms analyzed is related to long term human landscape interactions because deforestation and land use changes started in the neolithic ca 5 5 ka bc causing intensification of soil erosion processes willful and continuous interference by man into natural environment began at that time thus human impact is responsible for acceleration of runoff and mobilization of sediment which formed alluvial fans at the mouths of episodically drained valleys the objectives of this study are 1 to measure the morphological and topographical characteristics of the fans 2 to describe and analyze the inner structures of the alluvial fans analyzed and 3 to date the alluvial fan deposition the alluvial fans are mainly formed of silty clayey massive sediments the gravel sand layers occurring in two exposures indicate the incision of the valleys in the older pleistocene sediments underlying the loess upland deposits and intensive phases of erosion in the course of which coarser material could have been transported radiocarbon dating of the peat filling the bottoms of the valleys and underlying the mineral deposits of the fans indicates that sediment transfer from cultivated valley slopes and its deposition at the mouth of the valleys was recorded in alluvial fan sediments by the neolithic 6895 140 bp during this period erosion was probably intensified by a moister climate radiocarbon dating of organic layers which were discovered inside the sediments of two fans show that the youngest dated stage of intensified erosion took place in early medieval times when the glubczyce plateau was colonized again by slavs after the settlement depression during the migration period

geologic map of the northern hemisphere of vesta based on dawn framing camera fc images abstract the dawn framing camera fc has imaged the northern hemisphere of the asteroid 4 vesta at high spatial resolution and coverage this study represents the first investigation of the overall geology of the northern hemisphere 22 90 n quadrangles av 1 2 3 4 and 5 using these unique dawn mission observations we have compiled a morphologic map and performed crater size frequency distribution csfd measurements to date the geologic units the hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to 200 km in diameter the most widespread unit is a plateau cratered highland unit similar to although of lower elevation than the equatorial vestalia terra plateau large scale troughs and ridges have regionally affected the surface between 180 e and 270 e these tectonic features are well developed and related to the south pole veneneia impact saturnalia fossae trough unit elsewhere on the hemisphere they are rare and subdued saturnalia fossae cratered unit in these pre rheasilvia units we observed an unexpectedly high frequency of impact craters up to 10 km in diameter whose formation could in part be related to the rheasilvia basin forming event the rheasilvia impact has potentially affected the northern hemisphere also with s n small scale lineations but without covering it with an ejecta blanket post rheasilvia impact craters are small

vestan lithologies mapped by the visual and infrared spectrometer on dawn we present global lithological maps of the vestan surface based on dawn mission s visible infrared vir spectrometer acquisitions with a spatial sampling of 200 m the maps confirm the results obtained with the data set acquired by vir with a spatial sampling of 700 m that the reflectance spectra of vesta s surface are dominated by pyroxene absorptions that can be interpreted within the context of the distribution of howardites eucrites and diogenites heds the maps also partially agree with the ground and hubble space telescope observations they confirm the background surface being an assemblage of howardite or polymict eucrite as well as the location of a diogenitic rich spot however there is no evidence of extended olivine rich regions in the equatorial latitudes diogenite is revealed on the rheasilvia basin floor indicating that material of the lower crust mantle was exposed vir also detected diogenites along the scarp of matronalia rupes and the rims of severina and a nearby unnamed crater and as ejecta of antonia crater the diogenite distribution is fully consistent with petrological constraints although the mapped distribution does not provide unambiguous constraints it favors the hypothesis of a magma ocean

mineralogical and spectral analysis of vesta s gegania and lucaria quadrangles and comparative analysis of their key features abstract this work is aimed at developing and interpreting infrared albedo pyroxene and oh band depths and pyroxene band center maps of vesta s gegania and lucaria quadrangles obtained from data provided by the visible and infrared vir mapper spectrometer on board nasa s dawn spacecraft the gegania and lucaria quadrangles span latitudes from 22 s to 22 n and longitudes from 0 e to 144 e the mineralogical and spectral maps identify two large scale units on this area of vesta which extend eastwards and westward of about 60 e respectively the two regions are not associated to large scale geological units which have a latitudinal distribution rather than longitudinal but are defined by different contents of carbonaceous chondrites cc the eastern region poor in ccs is brighter and oh depleted whereas the western one rich in ccs is darker and oh enriched a detailed analysis of the small scale units in these quadrangles is also performed almost all the units show the typical correspondence between high albedo deep pyroxene bands short band centers and absence of oh and vice versa only a few exceptions occur such as the ejecta from the aelia crater where dark and bright materials are intimately mixed the most characteristic features of these quadrangles are the equatorial troughs and the lucaria tholus the equatorial troughs consist of graben i e a depression limited by two conjugate faults the graben do not present their own spectral signatures but spectral parameters similar to their surroundings in agreement to their structural origin this is observed also in graben outside the gegania and lucaria quadrangles however it is possible to observe other structural features such as tectonic grooves characterized by a changing composition and hence an albedo variation this result is confirmed not only by mineralogical maps of vesta but also by analyzing the virtis rosetta observations of lutetia the albedo change is instead a typical behavior of geomorphic grooves finally ridges are characterized by a bluer color and in some cases shorter band centers than their surroundings suggesting that they are composed of fresher materials we also performed a comparative analysis between the three tholi of vesta i e lucaria which gives the name to its quadrangle aricia in the marcia quadrangle and brumalia numisia quadrangle whereas brumalia tholus is a young magmatic intrusion the absence of diogenites the low albedo and the orientation of aricia and lucaria tholi suggest that they are older features which are covered by dark materials and therefore experienced a different geological history than brumalia

the sextilia region on asteroid 4vesta stratigraphy and variegation abstract mapping vesta surface composition in the sextilia region offers the unique possibility to investigate stratigraphic relationship of the surface compounds throughout the transition from rheasilvia vesta s prominent impact basin to vesta s northern equatorial region the vir data point to an upper eucrite dominated layer overlaying extended deposits of diogenite in the subsurface which reaches the surface at matronalia rupes the uplifted rim of the rheasilvia impact structure the dominance of diogenite in matronalia rupes suggests the existence of an extended diogenite rich layer and supports the magma ocean model as the most plausible formation model for vesta s interior local enrichment of diogenite outside of the rheasilvia impact basin are interpreted as outcrops of diogenite dominated breccia excavated during the rheasilvia impact event and re excavated by more recent impacts on the contrary the asymmetry in the distribution of diogenite rich outcrops in the norther parts i e the depletion of these deposits in the veneneia region is at odds with the equally distributed plutonic intrusions of diogenite rich material as proposed in the serial magmatism model but could be explained by an uneven distribution of its ejecta on vesta s surface due to an oblique rheasilvia impact

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

composition and mineralogy of dark material units on vesta vesta is the asteroid with the largest albedo variation among the known rocky solar system objects and shows a widespread occurrence of dark material dm and bright material bm units in the first observation phases by the dawn spacecraft two main extensions of low albedo areas were identified on vesta and found to be closely correlated with carbonaceous oh rich material in this work we use the hyperspectral data provided by the vir dawn imaging spectrometer onboard dawn to detect and analyze individual well defined dark material units we define dm units assuming a relative criterion i e reflectance lower than the surroundings by coupling visible and infrared images of the same area we are able to select real dark material units discarding false detections created by shadowing effects a detailed final catalogue of 123 dark units is presented containing the geographical parameters and the main spectral characteristics for each unit independently of the geological context of the dark units all dms show similar spectral properties dominated by the pyroxene absorption features as is the average spectrum of vesta this finding suggests a similar composition with the presence of darkening agents that also weaken pyroxene band depths the majority 90 of the dm units shows a positive correlation between low albedo and an oh band centered at 2 8 lm confirming the hypothesis that the darkening agents are carbonaceous chondrites probably delivered by low velocity impacts of primitive asteroids a comparison with laboratory spectra allows us to better constrain the size and the composition of the darkening agents these dm areas seem to be made of eucritic material the regolith grain size seems to be nearly constant around an average value of 25 lm and is quite homogenous at least in the first hundreds of meters beneath the vesta surface suggesting similar processing mechanisms for both dm and bm

complex transformation of the geomorphic regime of channels in the forefield of the moravskoslezske beskydy mts case study of the moravka river czech republic abstract this paper presents a complex analysis of both the contemporary and the historic development of the geomorphic regime of the transformed reach of the moravka river in the czech carpathians the assessment concentrates on the conditions and causes of the channel development in the last c 200 years compared with the state of european channels especially those of the carpathian zone the moravka r pattern has undergone a rapid change in the last 50 years particularly in connection with the active channel narrowing and massive incision the original anabranching river pattern has gradually been replaced by a simple narrowed channel incised into the bedrock the average width of the moravka r active channel changed from 153 m in 1836 1852 and 165 m in 1876 1878 to 44 m in the year 2010 at some parts the original river bed has lowered as much as 8 m in the last 40 years which indicates an incision rate of 12 24 cm year these changes have been caused by strong anthropogenic impacts in the form of the river channel control bank stabilisation and weir and valley dam construction other reasons are related to land cover and land use changes a great influence on the contemporary processes is also exerted by the geological predisposition of the carpathian flysch lithology in channel bedrock particularly the occurrence of claystone layers that present little resistance to water erosion currently the deficit of transportable sedimentary material along with the increased transport capacity of the incised river bed has generated conditions for constantly intensifying erosion processes in the moravka r channel

geomorphology and structural geology of saturnalia fossae and adjacent structures in the northern hemisphere of vesta vesta is a unique intermediate class of rocky body in the solar system between terrestrial planets and small asteroids because of its size average radius of 263 km and differentiation with a crust mantle and core vesta s low surface gravity 0 25 m s2 has led to the continual absence of a protective atmosphere and consequently impact cratering and impact related processes are prevalent previous work has shown that the formation of the rheasilvia impact basin induced the equatorial divalia fossae whereas the formation of the veneneia impact basin induced the northern saturnalia fossae expanding upon this earlier work we conducted photogeologic mapping of the saturnalia fossae adjacent structures and geomorphic units in two of vesta s northern quadrangles caparronia and domitia our work indicates that impact processes created and or modified all mapped structures and geomorphic units the mapped units ordered from oldest to youngest age based mainly on cross cutting relationships are 1 vestalia terra unit 2 cratered highlands unit 3 saturnalia fossae trough unit 4 saturnalia fossae cratered unit 5 undifferentiated ejecta unit 6 dark lobate unit 7 dark crater ray unit and 8 lobate crater unit the saturnalia fossae consist of five separate structures saturnalia fossa a is the largest maximum width of 43 km and is interpreted as a graben whereas saturnalia fossa b e are smaller maximum width of 15 km and are interpreted as half grabens formed by synthetic faults smaller second order structures maximum width of 1 km are distinguished from the saturnalia fossae a first order structure by the use of the general descriptive term adjacent structures which encompasses minor ridges grooves and crater chains for classification purposes the general descriptive term minor ridges characterizes ridges that are not part of the saturnalia fossae and are an order of magnitude smaller maximum width of 1 km vs maximum width of 43 km shear deformation resulting from the large scale diameter of 100 km rheasilvia impact is proposed to form minor ridges 2 km to 25 km in length which are interpreted as the surface expression of thrust faults as well as grooves 3 km to 25 km in length and pit crater chains 1 km to 25 km in length which are interpreted as the surface expression of extension fractures and or dilational normal faults secondary crater material ejected from small scale and medium scale impacts diameters of 100 km are interpreted to form ejecta ray systems of grooves and crater chains by bouncing and scouring across the surface furthermore seismic shaking also resulting from small scale and medium scale impacts is interpreted to form minor ridges because seismic shaking induces flow of regolith which subsequently accumulates as minor ridges that are roughly parallel to the regional slope in this work we expand upon the link between impact processes and structural features on vesta by presenting findings of a photogeologic structural mapping study which highlights how impact cratering and impact related processes are expressed on this unique intermediate solar system body

surface expressions of structural features on eros abstract near shoemaker imaging of the asteroid eros has revealed a variety of surface forms that probably reflect underlying structures they range from global to local in scale the most prominent positive topographic feature is a long ridge rahe dorsum which extends over 18 km and has the morphology of a thrust fault two large ancient trough systems are also present grooves are ubiquitous commonly occur in suborthogonal sets and have linear or scalloped outlines the grooves on eros are similar in morphology and scale to those on other small bodies such as gaspra ida and phobos and are likely to have a similar mode of origin namely drainage of regolith into underlying fractures models that use groove dimensions as indicators of regolith thickness imply depths of up to several tens of meters many craters have been subjected to structural control resulting in squared outlines we find no evidence that specific groove sets are associated with individual impact events however evidence exists that preexisting structures have been reactivated by later impact activity the large scale of rahe dorsum and many grooves on eros s surface suggests that the asteroid is a largely coherent but fractured body

433 eros lineaments global mapping and analysis using images and laser ranging data from the near shoemaker mission we map lineaments on the surface of eros in order to investigate the relationship between surface morphology and interior structure several sets of lineations are clearly related to visible impact craters while others suggest that different parts of the asteroid may have undergone different stress histories some of these sets infer internal structure at least on a local level this structure may derive from eros parent body and suggest although largely coherent eros interior may have portions that have not undergone a common history

vesta s mineralogical composition as revealed by the visible and infrared spectrometer on dawn the dawn spacecraft mission has provided extensive new and detailed data on vesta that confirm and strengthen the vesta howardite eucrite diogenite hed meteorite link and the concept that vesta is differentiated as derived from earlier telescopic observations here we present results derived by newly calibrated spectra of vesta the comparison between data from the dawn imaging spectrometer vir and the different class of hed meteorites shows that average spectrum of vesta resembles howardite spectra nevertheless the vesta spectra at high spatial resolution reveal variations in the distribution of hed like mineralogies on the asteroid the data have been used to derive hed distribution on vesta reported in ammannito et al 2013 and to compute the average vestan spectra of the different hed lithologies reported here the spectra indicate that not only are all the different hed lithologies present on vesta but also carbonaceous chondritic material which constitutes the most abundant inclusion type found in howardites is widespread however the hydration feature used to identify carbonaceous chondrite material varies significantly on vesta revealing different band shapes the characteristic of these hydration features cannot be explained solely by infalling of carbonaceous chondrite meteorites and other possible origins must be considered the relative proportion of heds on vesta s surface is computed and results show that most of the vestan surface is compatible with eucrite rich howardites and or cumulate or polymict eucrites a very small percentage of surface is covered by diogenite and basaltic eucrite terrains are relatively few compared with the abundance of basaltic eucrites in the hed suite the largest abundance of diogenitic material is found in the rheasilvia region a deep basin where it clearly occurs below a basaltic upper crust however diogenite is also found elsewhere although the depth to diogenite is consistent with one magma ocean model its lateral extent is not well constrained

geologic mapping of vesta from 1994 hubble space telescope images we utilize the 56 images of asteroid 4 vesta obtained through four mineralogically diagnostic filters by the hubble space telescope zellneret al 1997 icarus to construct a geologic map vesta s surface is found to be geologically diverse and to be dichotomous at a hemispheric scale the eastern hemisphere longitude definition from thomaset al 1997 icarus is dominated by units interpreted to be impact excavated plutonic material composed of magnesium rich and calcium poor pyroxene the mineralogy of this region is most analogous to diogenite meteorites several eastern hemisphere units which have the deepest and broadest 1 m absorption bands may contain a substantial olivine component the locations of these units are consistent with a previous map based on rotationally resolved groundbased spectroscopy gaffey 1997 icarus the western hemisphere is dominated by units interpreted to consist of a single component of iron rich and relatively calcium rich pyroxene analogous to surface basalts such as eucrite meteorites we investigate the spectral properties of 20 representative surface regions and find a correlation between the 1 m absorption band depth and albedo the units with lower albedos have shallower band depths such a relation could arise from differences in lithologies differences in surface particle sizes or from a weathering effect which decreases albedo and band depth over time because of vesta s geologic diversity and hemispheric dichotomy it is apparent that any major impact events such as those possibly related to the formation of the vesta family binzel and xu 1993 science260 186 191 did not globally resurface the planet the spectral evidence for remnants of a basaltic crust implies that the oldest units on the surface date back to the time of their emplacement most likely 4 5 byr ago if a weathering process exists which alters the albedo then the lowest albedo units such as the feature with the proposed name olbers most likely represent remnants of vesta s ancient basaltic crust

large scale troughs on vesta a signature of planetary tectonics abstract images of vesta taken by the dawn spacecraft reveal large scale linear structural features on the surface of the asteroid we evaluate the morphology of the vesta structures to determine what processes caused them to form and what implications this has for the history of vesta as a planetary body the dimensions and shape of these features suggest that they are graben similar to those observed on terrestrial planets not fractures or grooves such as are found on smaller asteroids as graben their vertical displacement versus length relationship could be evaluated to describe and interpret the evolution of the component faults linear structures are commonly observed on smaller asteroids and their formation has been tied to impact events while the orientation of the large scale vesta structures does imply that their formation is related to the impact events that formed the rheasilvia and veneneia basins their size and morphology is greatly different from impact formed fractures on the smaller bodies this is consistent with new analyses that suggest that vesta is fully differentiated with a mantle and core we suggest that impact into a differentiated asteroid such as vesta could result in graben while grooves and fractures would form on undifferentiated asteroids

compositional variations in the vestan rheasilvia basin abstract we present and describe the maps of spectral parameters such as pyroxene band centers and depths reflectance at 1 4 m and 2 8 m band depth in the rheasilvia quadrangle we found a broad anti correlation between pyroxene band centers and depths while the reflectance is not correlated with the pyroxene spectral parameters in addition we found that the rheasilvia quadrangle is free of oh absorption signatures we also derived lithological maps with improvements in the spatial resolution with respect to previous lithological maps of the same region we confirm that the central mound is dominated by eucritic howarditic pyroxene while diogenitic lithology has been found mainly in a region delineated by tarpeia severina and mariamne craters we found small scale variations in the composition of pyroxene these variations identify lithological units that extend for tens of km although small units of less than 1 km have also been found we consider this fact as an indication of a high level of compositional heterogeneity within the vestan crust

composition of the rheasilvia basin a window into vesta s interior 1 the estimated excavation depth of the huge rheasilvia impact basin is nearly twice the likely thickness of the vestan basaltic crust so the mantle should be exposed spectral mapping by the dawn spacecraft reveals orthopyroxene rich materials similar to diogenite meteorites in the deepest parts of the basin and within its walls significant amounts of olivine are predicted for the mantles of bulk chondritic bodies like vesta and its occurrence is demonstrated by some diogenites that are harzburgite and dunite however olivine has so far escaped detection by dawn s instruments spectral detection of olivine in the presence of orthopyroxene is difficult in samples with 25 olivine and olivine in rheasilvia might have been diluted during impact mixing or covered by the collapse of basin walls the distribution of diogenite inferred from its exposures in and around rheasilvia provides a geologic context for the formation of these meteorites but does not clearly distinguish between a magmatic cumulate versus partial melting restite origin for diogenites the former is favored by geochemical arguments and crystallization in either a magma ocean or multiple plutons emplaced near the crust mantle boundary is permitted by dawn observations

color and albedo heterogeneity of vesta from dawn multispectral images 0 44 to 0 98 m of asteroid 4 vesta obtained by the dawn framing cameras reveal global color variations that uncover and help understand the north south hemispherical dichotomy the signature of deep lithologies excavated during the formation of the rheasilvia basin on the south pole has been preserved on the surface color variations band depth spectral slope and eucrite diogenite abundance clearly correlate with distinct compositional units vesta displays the greatest variation of geometric albedo 0 10 to 0 67 of any asteroid yet observed four distinct color units are recognized that chronicle processes including impact excavation mass wasting and space weathering that shaped the asteroid s surface vesta s color and photometric diversity are indicative of its status as a preserved differentiated protoplanet

detection of new olivine rich locations on vesta abstract the discovery of olivine on vesta s surface by the vir imaging spectrometer onboard the dawn space mission has forced us to reconsider our views of vestan petrogenetic models olivines were expected to be present in the interior of vesta in the mantle of a vertically layered body as invoked by the magma ocean models or at the base or within the mantle crust boundary as proposed by fractionation models olivines have been detected by vir dawn in two wide areas near arruntia and bellicia regions located in the northern hemisphere interestingly these olivine rich terrains are far from the rheasilvia and the more ancient veneneia basins which are expected to have excavated the crust down to reach the mantle in this work we present our attempts to identify other undetected olivine rich areas on vesta by using spectral parameters sensitive to olivine such as the band area ratio bar and other specific parameters created for the detection of olivines on mars forsterite fayalite and a generic olivine index as a preliminary step we calibrated these parameters by means of vis ir spectra of different hed meteorite samples behaviors versus sample grain size and albedo were analyzed and discussed we selected the bar and the forsterite index as the best parameters that can be used on vesta a cross correlation analysis has been applied in order to detect olivine signature on the vir hyperspectral cubes these detections have then been confirmed by an anti correlation analysis between the bar and one of the olivine parameters independent of the first method applied in agreement with the recent discovery arruntia and bellicia were found to be as the most olivine rich areas i e where the parameter values are strongest in addition we detected 6 new regions all but one located in the vesta north hemisphere this result confirms again that the old petrogenetic models cannot be straightforwardly applied to vesta and should be reshaped in the view of these new detections an alternative and very recent option can be represented by the model according to which surface eruption of material from the mantle including olivine can reach the surface of vesta

human and climate impact on catchment development during the holocene geul river the netherlands interest in the holocene development of small to medium sized river catchments in western and central europe in relation to changes in land use and climate has increased over the past years in this study we reconstruct the holocene landscape development and fluvial dynamics of the geul river the netherlands and the main forcing mechanisms of environmental change field studies were carried out and we used osl and 14c dating methods to reconstruct the holocene valley development our study shows that 2 periods of deforestation during the roman period and the high middle ages led to severe soil erosion and increased floodplain sedimentation in the catchment of the geul river possibly combined with periods of increased wetness during the high middle ages alluvial fans have been active since the roman deforestation phase our results show that the geul catchment is highly sensitive to changes in land use