mineralogical analysis of the ac h 6 haulani quadrangle of the dwarf planet ceres abstract ac h 6 haulani is one of five quadrangles that cover the equatorial region of the dwarf planet ceres this quadrangle is notable for the broad spectrally distinct ejecta that originate from the crater haulani which gives the name to the quadrangle these ejecta exhibit one of the most negative bluest visible to near infrared spectral slope observed across the entire body and have distinct color properties as seen in multispectral composite images besides haulani here we investigate a broader area that includes other surface features of interest with an emphasis on mineralogy as inferred from data obtained by dawn s visible infrared mapping spectrometer vir combined with multispectral image products from the dawn framing camera fc so as to enable a clear correlation with specific geologic features our analysis shows that crater haulani stands out compared to other surface features of the quadrangle albedo maps obtained in the near infrared range at 1 2 m and 1 9 m reveal that the floor and ejecta of haulani are indeed a patchwork of bright and dark material units visible to near infrared spectral slopes display negative values in crater haulani s floor and ejecta highlighting bluish younger terrains diagnostic spectral features centered at 2 7 m and 3 1 m respectively indicate a substantial decrease in the abundances of magnesium bearing phyllosilicates and ammoniated phyllosilicates in crater haulani s floor and bright ejecta similar but less prominent spectral behavior is observed in other geologic features of this quadrangle while the general trend in quadrangle ac h 6 for these two mineral species is to increase from the northwest to the southeast however it is worth noting that the correlation between the 2 7 m and 3 1 m spectral parameters is generally strong in the haulani crater s area but much weaker elsewhere which indicates a variable degree of mixing between these two major mineral phases in moving away from the crater finally the region of crater haulani displays a distinct thermal signature and a local enhancement in calcium and possibly sodium carbonate minerals which is hardly found in the rest of the quadrangle and is likely the result of intense hydrothermal processes following the impact event these evidences all together confirm the young age of crater haulani as they have not been erased or made elusive by space weathering processes

spectral investigation of quadrangle ac h 3 of the dwarf planet ceres the region of impact crater dantu abstract mapping ceres surface composition in the dantu region located between 21 66 n and 90 180 e offers the unique possibility to investigate changes in the surface composition related to different stratigraphic levels of ceres crust dantu is located in a huge depression named vendimia planitia which possibly represents a completely degraded impact basin formed in the beginning of ceres geological history most parts of this depression are characterized by strong phyllosilicate absorptions which are stronger than elsewhere on ceres surface this spectral signature possibly is related to the material emplaced at the time of the vendimia impact event excavating material from deeper regions of ceres crust subsequent impacts in this basin reach far deeper into ceres crust than any impact events outside of vendemia planitia which could explain the spectral signature of dantu possibly pointing to a higher concentration of ammonium bearing phyllosilicates in ceres deeper crust spectral differences with respect to the small fresh craters on dantu s floor are probably related to grain size effects causing a bluish visible slope as observed by fresh impact craters on other places on ceres the local enrichment of carbonates in the dantu area could also be associated with the impact event and may have been formed by additional impact triggered and or post impact alteration processes

dawn arrives at ceres exploration of a small volatile rich world on 6 march 2015 dawn arrived at ceres to find a dark desiccated surface punctuated by small bright areas parts of ceres surface are heavily cratered but the largest expected craters are absent ceres appears gravitationally relaxed at only the longest wavelengths implying a mechanically strong lithosphere with a weaker deep interior ceres dry exterior displays hydroxylated silicates including ammoniated clays of endogenous origin the possibility of abundant volatiles at depth is supported by geomorphologic features such as flat crater floors with pits lobate flows of materials and a singular mountain that appears to be an extrusive cryovolcanic dome on one occasion ceres temporarily interacted with the solar wind producing a bow shock accelerating electrons to energies of tens of kilovolts

exposed h2o rich areas detected on ceres with the dawn visible and infrared mapping spectrometer abstract h2o rich materials are locally exposed at the surface of ceres as discovered from infrared reflectance spectra of the visible and infrared mapping spectrometer vir of the dawn mission nine locations on ceres exhibit diagnostic absorption bands of the h2o molecule at 2 00 1 65 and 1 28 m the detections are all consistent with h2o ice mixed with low albedo components all the reported h2o exposures occur at latitudes poleward of 30 in fresh craters near rim shadows have a surface area

resolved spectrophotometric properties of the ceres surface from dawn framing camera images we present a global spectrophotometric characterization of the ceres surface using dawn framing camera fc images we identify the photometric model that yields the best results for photometrically correcting images corrected fc images acquired on approach to ceres were assembled into global maps of albedo and color generally albedo and color variations on ceres are muted the albedo map is dominated by a large circular feature in vendimia planitia known from hst images li et al 2006 and dotted by smaller bright features mostly associated with fresh looking craters the dominant color variation over the surface is represented by the presence of blue material in and around such craters which has a negative spectral slope over the visible wavelength range when compared to average terrain we also mapped variations of the phase curve by employing an exponential photometric model a technique previously applied to asteroid vesta schroder et al 2013b the surface of ceres scatters light differently from vesta in the sense that the ejecta of several fresh looking craters may be physically smooth rather than rough high albedo blue color and physical smoothness all appear to be indicators of youth the blue color may result from the desiccation of ejected material that is similar to the phyllosilicates water ice mixtures in the experiments of poch et al 2016 the physical smoothness of some blue terrains would be consistent with an initially liquid condition perhaps as a consequence of impact melting of subsurface water ice we find red terrain positive spectral slope near ernutet crater where de sanctis et al 2017 detected organic material the spectrophotometric properties of the large vendimia planitia feature suggest it is a palimpsest consistent with the marchi et al 2016 impact basin hypothesis the central bright area in occator crater cerealia facula is the brightest on ceres with an average visual normal albedo of about 0 6 at a resolution of 1 3 km per pixel six times ceres average the albedo of fresh bright material seen inside this area in the highest resolution images 35 m per pixel is probably around unity cerealia facula has an unusually steep phase function which may be due to unresolved topography high surface roughness or large average particle size it has a strongly red spectrum whereas the neighboring less bright vinalia faculae are neutral in color we find no evidence for a diurnal ground fog type haze in occator as described by nathues et al 2015 we can neither reproduce their findings using the same images nor confirm them using higher resolution images fc images have not yet offered direct evidence for present sublimation in occator

the surface composition of ceres ezinu quadrangle analyzed by the dawn mission abstract we studied the surface composition of ceres within the limits of the ezinu quadrangle in the ranges 180 270 e and 21 66 n by analyzing data from dawn s visible and near infrared data from the visible and infrared mapping spectrometer and from multispectral images from the framing camera our analysis includes the distribution of hydroxylated minerals ammoniated phyllosilicates carbonates the search for organic materials and the characterization of physical properties of the regolith the surface of this quadrangle is largely homogenous except for small high albedo carbonate rich areas and one zone on dark lobate materials on the floor of occator which constitute the main topics of investigation 1 carbonate rich surface compositions are associated with h2o ice rich crust weaker absorption bands of hydroxylated and ammoniated minerals over the carbonate rich areas can be explained by higher abundances of carbonates at the topmost surface 2 dark smooth lobate materials at the foot of occator s northeastern wall possibly reveal fresh slumping of phyllosilicate rich materials with fine grain size or local enrichment in carbon rich materials such as tholins 3 the deeper absorption band depth of oh and nh4 on the rim of several impact craters is one observation that is consistent with a stratification of the phyllosilicate abundance that has been inferred previously from global investigations

mineralogical analysis of quadrangle ac h 10 rongo on the dwarf planet ceres abstract quadrangle ac h 10 rongo lat 22 s to 22 n lon 288 360 e shows a fairly homogeneous topography with the presence of notable elevations such as ahuna mons liberalia mons and part of samhain and uhola catenae the deepest areas correspond to the rongo crater region the areas between samhain and uhola catenae and the region of the quadrangle south of ahuna mons a substantial variability in the 2 7 m band depth distribution is observed across the rongo quadrangle indicating an east west gradient in the abundance of mg phyllosilicates the nh4 phyllosilicates distribution appears quite homogeneous except some localized regions such as crater haulani s ejecta the flanks of ahuna mons and crater begbalel the two band depths at 2 7 and 3 1 m display an overall low correlation suggesting a variable degree of mixing between mg phyllosilicates and nh4 phyllosilicates at the local scale mineralogical phases other than phyllosilicates are observed quadrangle rongo includes sodium carbonate rich regions such as the flanks of ahuna mons the ejecta of xevioso crater located in the southern edge of liberalia mons and crater begbalel which often display a reduction in both the 2 7 and 3 1 m band depths associated with an increased band depth at 4 m related to the presence of na rich carbonate phases this suggests recent hydrothermal activity in this area due to several episodes of cryovolcanism or impacts that unveiled a peculiar composition in the shallow subsurface alternatively the crust in this region might show a variable degree of compactness such that the formation of na carbonates is favored only in specific locations de sanctis et al 2016 ruesch et al 2016 zambon et al 2017 from a geological standpoint quadrangle ac h 10 rongo shows a correlation between its two main geologic units platz et al 2017 and the distribution of mg phyllosilicates suggesting a link between geology and mineralogy in this area

u pb rb sr and sm nd chronology of granitic basement hydrothermal albitites and uranium mineralization lagoa real south bahia brazil the granites orthogneisses hydrothermal albitities and rocks which have suffered uranium mineralization from the lagoa real district south state of bahia brazil have been investigated by u pb rb sr and sm nd techniques u pb values on zircons from the granitic protolith give an age of 1725 ma u pb on u mineralization dates the primary mineralization at 1395 ma and indicates a reworking at 480 ma which may represent the age of the thrusting of the lagoa real complex over espinhaco metasediments during the brazilian orogeny these two dates are given by rb sr on albitites but from sparse information and are not supported by unequivocal arguments the uranium deposition and sodium metasomatism however cannot be linked either with the thermal history of the granite or with brazilian thrusting sm nd gives scattered results which are suggestive of autochtonous reworkings of rees these results lead to the following suggestions 1 magmatic activity of subalkaline affinity existed within the sao francisco craton at about 1 7 ga 2 such subalkaline plutons are likely sources for u mineralization 3 at about 1 4 ga an unknown event caused hydrothermal activity leading to u deposition at lagoa real 4 brazilian overthrusting at about 480 ma did not play any genetic role in the hydrothermal activity

mineralogical mapping of the kerwan quadrangle on ceres abstract the ceres surface is globally composed of mg phyllosilicates ammoniated clays carbonates and dark components to obtain a more detailed mineralogical and geological investigation the dwarf planet surface has been divided into fifteen quadrangles the aim of this work is to investigate the abundance of phyllosilicates and ammoniated clays in the kerwan quadrangle classified as ac h 7 and spanning from 22 s to 22 n in latitude and from 72 e to 144 e in longitude maps of band depth distribution at 2 7 m and 3 1 m have been performed and compared with a map of geometric albedo estimated at 1 2 m phyllosilicates and ammoniated clays generally correlate in the kerwan quadrangle even if departure from this behavior is observed in the floor of kerwan inamahari and homsuk craters the greatest abundance of ammoniated phyllosilicates is found in rao and kerwan ejecta while bonsu and tafakula floors are the most depleted in volatile as well as inamahari and dantu ejecta six bright spots are detected in the kerwan quadrangle and the one richest in carbonate is related to dantu ejecta in the southeast region some younger features such as rao or kerwan ejecta show deeper band depths than older terrain a contrast trend with respect to the entire ceres surface since this correlation is observed in a few other places on other quadrangles but not on the entire ceres surface it is possible that recent impact events could have been masked this correlation

mineralogy of the urvara yalode region on ceres abstract we studied the distribution in the urvara yalode region of ceres latitudes 21 66 s longitudes 180 360 e of main spectral parameters derived from the vir imaging spectrometer onboard the nasa dawn spacecraft as an overall study of ceres mineralogy reported in this special issue in particular we analyzed the distribution of reflectance at 1 2 m band depth at 2 7 and 3 1 m ascribed to magnesium and ammoniated phyllosilicates respectively whereas the average band depths of this region are lower than eastern longitudes reflecting the e w dichotomy of abundance of phyllosilicates on ceres spectral variations inside this region are observed in the following units a the central peak of the urvara crater 45 9 s 249 2 e 170 km in diameter showing a deep 3 1 m band depth indicating an ammonium enrichment b the cratered terrain westwards of the yalode basin 42 3 s 293 6 e 260 km in diameter where absorption bands are deeper probably due to absence of phyllosilicates depletion following the yalode impact c the hummocky cratered floor of yalode and besua 42 4 s 300 2 e craters characterized by lower albedo and band depths probably due to different roughness d consus 21 s 200 e and tawals 39 1 s 238 e craters whose albedo and band depths decreasing could be associated to different grain size or abundance of dark materials twenty two small scale i e lower than 400 m bright spots are observed because their composition is similar to the ceres average a strong mixing may have occurred since their formation

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

u pb geochronology of archean magmatism and basement reactivation in the carajas area amazon shield brazil abstract the archean carajas subprovince is a metallogenic district bif bauxite cu ni mn au located in the easternmost amazonian craton in brazil the main conclusions from a u pb study of the itacaiunas supergroup and a locality in the xingu complex are the following the xingu basement complex the oldest unit underwent migmatization at 2859 2 ma and also grew new zircon at 2851 4 ma the luanga mafic intrusion is 2763 6 ma old and coeval with the 2759 2 ma felsic volcanics of the grao para group amphibolites from the salobo group contain 2851 ma zircons were metamorphosed 2761 3 ma and intruded by granitic veins ca 2758 ma at the time of grao para magmatism and also grew new zircon at 2732 2742 ma the data indicate that the salobo group is part of the xingu complex and not of the itacaiunas supergroup as heretofore believed the pojuca group possibly coeval with the salobo group was metamorphosed at 2732 3 ma a late archean reactivation event of regional extent is marked by titanite growth at 2581 5 ma in the mirim area intrusion of the old salobo granite at 2573 2 ma new zircon growth in salobo group amphibolites at 2555 4 3 ma and monazite growth in a metamorphosed iron formation at 2551 2 ma in addition k metasomatism associated with shear zones formed titanite in salobo group amphibolites at 2497 5 ma and new titanite at 2519 5 ma in the xingu complex events in the 2581 2497 ma interval are probably associated with the latest activity of a wnw ese sinistral shear system which could also be responsible for the establishment of a transtensional basin filled by the volcano sedimentary sequence of the grao para bahia and rio fresco groups finally undeformed proterozoic granitoid intrusions were dated at 1883 2 ma cigano 1883 5 2 ma musa 1880 2 ma carajas and 1874 2 ma pojuca

geological mapping of the ac 10 rongo quadrangle of ceres abstract the dawn spacecraft arrived at dwarf planet ceres in spring 2015 and imaged its surface from four successively lower polar orbits at ground sampling dimensions between 1 3 km px and 35 m px to understand the geological history of ceres a mapping campaign was initiated to produce a set of 15 quadrangle based geological maps using the highest resolution framing camera imagery here we present the geological map of the ac 10 rongo quadrangle which is located at the equator encompassing the region from 22 n to 22 s and 288 to 360 e the total relief within the quadrangle is 11 1 km with altitudes ranging from about 7 3 km to 3 8 km we identified nine geological units based on surface morphology and surface textural characteristics the dominant and most widespread unit is the cratered terrain crt representing ancient reworked crustal material its consistent formation age across the quadrangle is 1 8 ga two edifices unit th ahuna mons and an unnamed tholus within begbalel crater are interpreted to be of cryo volcanic origin the southwest portion of the quadrangle is dominated by ejecta material ye emplaced during the formation of the 260 km diameter yalode impact basin at about 580 ma rayed crater ejecta material cr is dominant in the eastern part of the quadrangle but also occurs in isolated patches up to a distance of 455 km from the 34 km diameter source crater haulani the remaining five geological units also represent impact crater materials degraded rim crdeg bright crater cb hummocky floor cfh talus ta and crater c materials widespread yalode and haulani ejecta materials can potentially be utilised as stratigraphic markers therefore it is essential to consistently map their full areal extent and to date their formations using impact crater statistics

mineralogy of the occator quadrangle abstract we present an analysis of the areal distribution of spectral parameters derived from the vir imaging spectrometer on board nasa dawn spacecraft specifically we studied the occator quadrangle of ceres which is bounded by latitudes 22 s to 22 n and longitudes 214 e to 288 e as part of the overall study of ceres surface composition reported in this special publication the spectral parameters used are the photometrically corrected reflectance at 1 2 m the infrared spectral slope 1 1 1 9 m and depths of the absorption bands at 2 7 m and 3 1 m that are ascribed to hydrated and ammoniated materials respectively we find an overall correlation between 2 7 m and 3 1 m band depths in agreement with ceres global behavior and band depths are shallower and the spectral slope is flatter for younger craters probably due to physical properties of regolith such as grain size spectral variations correlated with the tali geological unit also suggest differences in physical properties the deepest band indicating enrichment of ammoniated phyllosilicates are associated with ejecta generated by impacts that occurred in southern quadrangles the most peculiar region of this quadrangle is the occator crater 20 n 240 e the internal crater area contains two faculae which are the brightest areas on ceres due to exposure of sodium carbonates and by two types of ejecta dark and bright with different spectral properties probably due to different formation evolution or age

the spectral parameter maps of ceres from nasa dawn vir data abstract this article presents the spectral parameter maps used in this surface composition of ceres special issue the definition and use of spectral parameters has always played a fundamental role in understanding the properties and composition of a planetary surface mapping proper spectral parameters shows the global mineralogical diversity across ceres in this work we discuss the production process of ceres spectral parameter maps derived by the data of the visible and infrared mapping spectrometer vir onboard nasa s dawn mission we describe the data processing of the vir spectra and the procedure to retrieve the geometries latitude longitude and illumination angles of the acquired data spectra and geometries are used to project and mosaic this data to produce geographic information system compatible spectral parameters maps of ceres an overview of the variability of the data across the quadrangles is given addressing the specific analysis to each quadrangle mapping paper included in this special issue

distribution of phyllosilicates on the surface of ceres the dwarf planet ceres is known to host phyllosilicate minerals at its surface but their distribution and origin have not previously been determined we used the spectrometer onboard the dawn spacecraft to map their spatial distribution on the basis of diagnostic absorption features in the visible and near infrared spectral range 0 25 to 5 0 micrometers we found that magnesium and ammonium bearing minerals are ubiquitous across the surface variations in the strength of the absorption features are spatially correlated and indicate considerable variability in the relative abundance of the phyllosilicates although their composition is fairly uniform these data along with the distinctive spectral properties of ceres relative to other asteroids and carbonaceous meteorites indicate that the phyllosilicates were formed endogenously by a globally widespread and extensive alteration process

pitted terrains on 1 ceres and implications for shallow subsurface volatile distribution prior to the arrival of the dawn spacecraft at ceres the dwarf planet was anticipated to be ice rich searches for morphological features related to ice have been ongoing during dawn s mission at ceres here we report the identification of pitted terrains associated with fresh cerean impact craters the cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on mars where ice is implicated in pit development and vesta where the presence of ice is debated we employ numerical models to investigate the formation of pitted materials on ceres and discuss the relative importance of water ice and other volatiles in pit development there we conclude that water ice likely plays an important role in pit development on ceres similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization

spectral analysis of ahuna mons from dawn mission s visible infrared spectrometer ahuna mons is the highest mountain on ceres a unique complex in terms of size shape and morphology ahuna is bordered by flanks of the talus around its summit recent work by ruesch et al 2016 based on dawn s framing camera images shed light on the possible origin of ahuna mons according to ruesch et al 2016 ahuna mons is formed by a volcanic process involving the ascent of cryomagma and extrusion onto the surface followed by dome development and subsequent spreading here we analyzed in detail the composition of ahuna mons using data acquired by the visible and infrared spectrometer aboard dawn the spectral analysis reveals a relatively high abundance of carbonates and a non homogeneous variation in carbonates composition and abundance along ahuna s flanks associated with a lower amount of the ceres s ubiquitous nh4 phyllosilicates over a large portion of the flanks the grain size is coarser on the flanks than in the surrounding regions suggesting the presence of fresher material also compatible with a larger abundance of carbonates thermal variations are seen in ahuna supporting the evidence of different compactness of the surface regolith in specific locations results of the spectral analysis are consistent with a possible cryovolcanic origin which exposed fresher material that slid down on the flanks

mineralogical mapping of coniraya quadrangle of the dwarf planet ceres abstract ceres has been explored by nasa dawn spacecraft which allowed for the discovery of the main mineralogical and compositional characteristics of ceres surface here we use mainly data from the visible and infrared imaging spectrometer vir in order to investigate the main spectral characteristics of the quadrangle ac h 2 coniraya one of the 15 quads in which ceres surface has been divided coniraya quadrangle is characterized by the presence of mostly highly degraded impact craters of diameters between 50 and 200 km and clusters of small to midsize impact craters although the composition over the quadrangle appears to be quite uniform significant differences have been detected between different craters by spectral parameters analysis and spectral modeling ernutet crater presents two regions with very peculiar band at 3 4 m typical of organics aliphatic material one region result to be correlated with larger amount of carbonates the other region does not present such correlation ikapati crater shows strong absorption bands at 4 0 m indicating the presence of na carbonates in the floor and ejecta ikapati gaue and other craters present smaller spectral features of nh4 and or oh stretching suggesting a volatile depletion process induced by the heating of the impact event

thermal stability of ice on ceres with rough topography the dwarf planet ceres may have an ice rich crust and subsurface ice exposed by impacts or endogenic activity would be subject to sublimation we model surface and subsurface temperatures on ceres to assess lifetimes of water ice and other volatiles topographic shadowing allows a small but non negligible fraction 0 4 of ceres surface to be perennially below the 110 k criterion for 1 gyr of stability these areas are found above 60 latitude other molecules ch3oh nh3 so2 co2 may be cold trapped in smaller abundances a model for the transport gravitational escape and photoionization of h2o molecules suggests net accumulation in the cold traps buried ice is stable within a meter for 1 gyr at latitudes higher than 50 an illuminated polar cap of water ice would be stable within a few degrees of the poles only if it maintained a high albedo 0 5 at present obliquity if the obliquity exceeded 5 in the geologically recent past then a putative polar cap would have been erased at latitudes 0 30 ice is stable under solar illumination only briefly 10 100 yr unless it has high albedo and thermal inertia in which case lifetimes of 104 yr are possible finally a small hemispheric asymmetry exists due to the timing of ceres perihelion passage which would lead to a detectable enhancement of ice in the northern hemisphere if the orbital elements vary slowly relative to the ice accumulation rate our model results are potentially testable during the dawn science mission

the mineralogy of ceres nawish quadrangle abstract quadrangle ac h 08 nawish is located in the equatorial region of ceres lat 22 s 22 n lon 144 e 216 e and it has variable mineralogy and geology here we report on the mineralogy using spectra from the visible and infrared vir mapping spectrometer onboard the nasa dawn mission this quadrangle has two generally different regions the cratered highlands of the central and eastern sector and the eastern lowlands we find this dichotomy is also associated with differences in the nh4 phyllosilicates distribution the highlands in the eastern part of the quadrangle appear depleted in nh4 phyllosilicates conversely to the lowlands in the north western side the mg phyllosilicates distribution is quite homogeneous across nawish quadrangle except for few areas the 2 7 m band depth is lower in the south eastern part e g in the azacca ejecta and consus crater ejecta and the band depth is greatest for the nawish crater ejecta and indicates the highest content of mg phyllosilicates of the entire quadrangle our analysis finds an interesting relationship between geology mineralogy topography and the age in this quadrangle the cratered terrains in the highlands poor in nh4 phyllosilicates are older 2 ga conversely the smooth terrain such as with vindimia planitia is richer in ammonia bearing phyllosilicates and is younger 1 ga at the local scale ac h 8 nawish displays several interesting mineralogical features such as at nawish crater consus crater dantu and azzacca ejecta which exhibit localized na carbonates deposits this material is superimposed on the cratered terrains and smooth terrains and shows the typical depletion of phyllosilicates already observed on ceres in the presence of na carbonates

timing of optical maturation of recently exposed material on ceres on ceres multispectral imaging data from the dawn spacecraft show a distinct bluish characteristic for recently exposed material from the subsurface in for example crater ejecta ejecta blankets of presumably old craters show a more reddish spectrum we selected areas in which fresh material from the cerean subsurface was exposed at a specific time in the past and no later geologic process is expected to have changed its surface composition or its cratering record for each area we determined two color ratios and the crater retention age the measured color ratios show an exponential diminishment of the bluish characteristic over time although the cause of the color change remains uncertain the time dependent change in spectral properties is evident which could help identify the process

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

geomorphological evidence for ground ice on dwarf planet ceres despite evidence for an ice rich outer shell little water ice has been observed on the surface of ceres lobate morphologies observed on ceres that are increasingly prevalent towards the dwarf planet s poles are consistent with ice rich flows

ceres predictions for near surface water ice stability and implications for plume generating processes this paper will constrain the possible sources and processes for the formation of recently observed h2o vapor plumes above the surface of the dwarf planet ceres two hypotheses have been proposed 1 cryovolcanism where the water source is the mantle and the heating source is still unknown or 2 comet like sublimation where near surface water ice is vaporized by seasonally increasing solar insolation we test hypothesis 2 comet like near surface sublimation by using a thermal model to examine the stability of water ice in the near surface for a reasonable range of physical parameters thermal inertia surface roughness and slopes we find that water ice is only stable at latitudes higher than 40 60 these results indicate that either a the physical properties of ceres are unlike our expectations or b an alternative to comet like sublimation such as the cryovolcanism hypothesis must be invoked

geological and shrimp ii u pb constraints on the age and origin of the breves cu au w bi sn deposit carajas brazil the breves deposit in the carajas copper gold belt brazil a member of the cu au w bi sn group of deposits contains about 50 mt of 1 22 cu 0 75 g t au 2 4 g t ag 1 200 g t w 70 g t sn 175 g t mo and 75 g t bi it is hosted by sandstones and siltstones of the aguas claras formation minimum age of 2 681 5 ma in the roof zone of a complex highly altered granite intrusion the mineralisation is disseminated in a greisenized zone resulting from alteration of probable monzogranites and syenogranites the ore bearing greisen contains abundant xenomorphic quartz in association with fe chlorite and muscovite the gangue assemblage also includes fluorite tourmaline and minor amounts of monazite xenotime chlorapatite thorite zircon calcite siderite and bastnaesite copper mineralisation is dominated by chalcopyrite associated with pyrite arsenopyrite pyrrhotite and molybdenite gold particles in equilibrium with native bismuth are common as inclusions in chalcopyrite the greisen contains sub economic concentrations of tungsten and niobium that are related to the presence of ferberite qitianlingite and nb rutile shrimp ii zircon dating of the host granites gives 207pb 206pb ages of 1 878 8 and 1 880 9 ma for two phases and a combined age of 1 879 6 ma shrimp ii dating of monazite and xenotime grains in late to post mineralisation veins gives a combined 207pb 206pb age of 1 872 7 ma indistinguishable from the ages of the granites this provides a genetic connection between the breves deposit and the ca 1 88 ga a type granite magmatism that typifies the carajas belt as part of a much larger intracratonic magmatic province that extends over much of the amazonian craton the recognition of this association has exploration implications not only for the geophysical signature of the granite roof zones but also for likely geochemical dispersion around the deposits of this type

an investigation of the bluish material on ceres the dwarf planet ceres shows spatially well defined regions which exhibit a negative blue spectral slope between 0 5 and 2 5 m comparisons with planetary bodies known to exhibit a blue slope and spectral properties of materials identified on ceres surface based on infrared wavelength signatures indicate the spectral changes could be related to physical properties of the surface material rather than variations in its composition the close association of bluish surface regions to fresh impact craters implies a possible relationship to an impact triggered alteration and or space weathering processes the bluish regions could be linked with blankets of ultra fine grains and partly amorphous phyllosilicates which form larger agglomerates due to the sticky behavior of impact induced phyllosilicate dust and or the amorphization of the ejecta material during the impact process space weathering processes micro meteoritic impacts temperature changes cause a reversal of the agglutination process and a re crystallization of the surface material with time resulting in a reddening of the spectral slope

cryogenic flow features on ceres implications for crater related cryovolcanism craters on ceres such as haulani kupalo ikapati and occator show postimpact modification by the deposition of extended plains material with pits multiple lobate flows and widely dispersed deposits that form a diffuse veneer on the preexisting surface bright material units in these features have a negative spectral slope in the visible range making it appear bluish with respect to the grey toned overall surface of ceres we calculate the drop height to runout length ratio of several flow features and obtain a coefficient of friction of 0 1 the results imply higher flow efficiency for flow features on ceres than for similar features on other planetary bodies with similar gravity suggesting low viscosity material the special association of flow features with impact craters could either point to an impact melt origin or to an exogenic triggering of cryovolcanic processes

ac h 11 sintana and ac h 12 toharu quadrangles assessing the large and small scale heterogeneities of ceres surface abstract mineralogical maps of the ac h 11 sintana and the ac h 12 toharu quadrangles of the dwarf planet ceres were produced in order to access the composition of this planetary body we used data from nasa s dawn spacecraft in particular the spectra returned by vir the imaging spectrometer on board different spectral parameters in the infrared range have been computed to study the composition of this portion of ceres surface and its large and small scale variability we studied the variation and distribution of the phyllosilicate bands at 2 73 m and 3 07 m the reflectance at 1 2 m and the overall spectrum in specific locations we did not observe variations of the center of the bands at 2 73 m and 3 07 m with the exception of a few pixels in the kupalo crater we found that this southern region extending from 0 to 180 and from 21 s to 66 s show an overall increase of phyllosilicate band intensity from the equatorial areas to the southern areas superimposed to the large scale trend we observe many smaller localized variations of band intensity the observed variations can indicate large and small scale heterogeneities in the abundance of the different species in the ceres subsurface however the small scale variation that is mostly associated with young craters can be also due to processes related with impacts such as de hydration or delivery of exogenous material that mixed with the original surface could change the band intensity several craters such as kupalo and juling show a different composition with respect to the background displaying water ice and sodium carbonates

compositional differences among bright spots on the ceres surface at the beginning of the ceres investigation the dawn nasa mission discovered a large bright spot bs in the occator crater floor several other smaller bright spots were discovered during the following phases of the mission in this paper a complete survey for the detection of bs on the ceres surface have been made by using the hyperspectral data acquired by visible and infrared mapping spectrometer vir the hyperspectral images span the spectral range from 0 2 to 5 m by using two channel the vis channel with a spectral sampling of 1 8 nm and a ir channel with a spectral sampling of 9 8 nm finally a catalogue of 92 bs has been compiled and their compositional properties have been examined in particular five spectral parameters have been applied to perform the analysis the photometrically corrected reflectance and four band depths related to spectral absorptions at 2 7 m oh fundamental indicative of phyllosilicates at 3 05 m due to ammoniated clays at 3 4 and 4 0 m carbonate overtones the 90 of bs are impact related features ejecta crater rim crater floor crater wall the two brightest bs cerealia and vinalia faculae are located on the occator crater floor most of bss show features similar to the average ceres surface which has low reflectance and is composed of mg phyllosilicates and ammoniated clays with a reduced abundance of mgca carbonates cerealia and vinalia faculae are a peculiar bs family with a high abundance of na carbonates and al rich phyllosilicates oxo and a companion bright spot represents a third category depleted in phyllosilicates and with a high to moderate albedo carbonate composition ranges from mg ca to na components haulani ernutet kupalo and other two bs s represent another group with intermediate properties between the typical bs and the oxo family they are moderately rich in carbonates and slightly depleted in mg and ammoniated phyllosilicates the four families probably explain a single evolutionary path followed by the bs from the formation to their maturity initially the very fresh bright spots would possess characteristics similar to cerealia and vinalia faculae with time salts and oh volatilize and a light mixing with surrounding material would produce oxo like bs s additional strong mixing would form haulani like bs which finally become a typical bright spots

mineralogy and temperature of crater haulani on ceres we investigate the region of crater haulani on ceres with an emphasis on mineralogy as inferred from data obtained by dawn s visible infrared mapping spectrometer vir combined with multispectral image products from the dawn framing camera fc so as to enable a clear correlation with specific geologic features haulani which is one of the youngest craters on ceres exhibits a peculiar blue visible to near infrared spectral slope and has distinct color properties as seen in multispectral composite images in this paper we investigate a number of spectral indices reflectance spectral slopes abundance of mg bearing and nh4 bearing phyllosilicates nature and abundance of carbonates which are diagnostic of the overall crater mineralogy plus a temperature map that highlights the major thermal anomaly found on ceres in addition for the first time we quantify the abundances of several spectral endmembers by using vir data obtained at the highest pixel resolution 0 1 km the overall picture we get from all these evidences in particular the abundance of na and hydrous na carbonates at specific locations confirms the young age of haulani from a mineralogical viewpoint and suggests that the dehydration of na carbonates in the anhydrous form na2co3 may be still ongoing

geologic mapping of the ac 11 sintana quadrangle assessing diverse crater morphologies abstract a geologic map at a scale of 1 1 000 000 of the ac 11 sintana quadrangle 21 66 s and 0 90 e from the dwarf planet ceres and based on data from nasa s dawn spacecraft was produced as part of a geologic mapping campaign in order to investigate the surface structure stratigraphy composition and surface modifying processes the sintana quadrangle is geologically dominated by cratered terrain with morphologically distinct crater types the most prominent craters sintana hamori jarimba tupo annona and darzamat have complex structures including smooth crater material covering their floors collapsed crater walls forming terraces and central ridges multiple gravity driven blocky mass wasting features indicate post impact crater modification and are indicative of an ice rich subsurface in which there is no topographic or structural evidence of endogenic activity visible in the quadrangle absolute age estimates suggest that the entire surface in the quadrangle was resurfaced 1 1 ga ago possibly by kerwan related impact induced melting

the unique geomorphology and structural geology of the haulani crater of dwarf planet ceres as revealed by geological mapping of equatorial quadrangle ac 6 haulani abstract the dwarf planet ceres has been explored by nasa s dawn spacecraft with the goal of characterizing its geology mineralogy topography shape and internal structure one outcome of this exploration is the production of geologic maps meant to unveil the geologic history of ceres in this paper we present the geologic map of the ac 6 haulani quadrangle lat 22 s 22 n long 0 72 e based on low altitude mapping orbit lamo 35 m pixel data supplemented with color and spectral data as well as a digital terrain model from the high altitude mapping orbit hamo 135 m pixel vertical accuracy of about 10 m the 34 km diameter haulani crater is one of the youngest features on ceres and the most prominent one in the quadrangle haulani was formed on a topographical transition in north south direction and shows a complex morphology with a variety of lobate flows and tectonic features multiple cracks and depressions around the crater indicate the failure of subsurface material these were likely formed by the subsidence of material due to the instability of the subsurface the mapping of ac 6 haulani suggests that ceres is built up of layers with different material properties we propose that ceres has a solid crust and a variable ice rich subsurface consistent with previous and recent models of ceres interior

mineralogy mapping of the ac h 5 fejokoo quadrangle of ceres abstract this paper focuses on the identification and distribution of compositional units and their stratigraphic relationships in the fejokoo quadrangle of ceres ac 5 located between 21 66 n and 270 360 e and named after one of its prominent and well preserved impact craters fejokoo centered at 26 n and 312 e in this quadrangle we observed that hydroxylated oh rich and ammoniated nh4 rich phyllosilicates are present everywhere in various abundances low abundance is observed on bright terrains and higher abundances are observed on lobate materials associated with craters carbonates are mostly correlated with the high albedo areas surrounding oxo 359 7 e 42 2 n and other major craters and are mixed with ceres most common surface composition type i e low albedo phyllosilicate rich material there are a few locations where carbonates and phyllosilicates co exist indicating a range of geological or chemical processes produced them in co existence no correlation between the surface composition and the age of the craters was found instead the composition observed on impact craters depends on the size of the impact and the composition of the different stratigraphic layers excavated the compositional interpretation inferred from dawn s visible infrared spectrometer data of the fejokoo quadrangle is consistent with the presence of an internal ocean that produced carbonates and phyllosilicates via aqueous alteration of minerals