steepland resources characteristics stability and micromorphology abstract steeplands of central america are a major land resource but due to population pressures they are rapidly being deforested leading to landscape instability microwatersheds of southern honduras were examined to correlate soil type landform slope gradient and slump potential soils most susceptible to slumping were moderately deep 0 5 1 m haplustalfs and haplustepts these soils occupy about 25 of the landscape and have slope gradients of 45 90 soils are developed on plagioclase rich andesitic parent material are loam to clay loam in texture and have high base status however due to weathering of parent material sand and silt fractions are dominated by quartz with smaller amounts of plagioclase vermiculite and kaolinite the a and b horizons have an open porphyric related distribution with plagioclase as the coarse fraction in a fine grained groundmass the andesitic parent rock contains abundant hydrothermally altered plagioclase phenocrysts in a single spaced porphyric related c f5 m ratio of 4 1 distribution some feldspars are partially to completely altered to clay pseudomorphs probably vermiculite microfabric analysis of soil and pararock did not show any striated b fabric indicative of shear failure however microfabrics do confirm translocated clay into the subsoil as typic pore coatings indicating long term landscape stability prior to deforestation

flooding of ganymede s bright terrains by low viscosity water ice lavas large regions of the jovian moon ganymede have been resurfaced but the means has been unclear suggestions have ranged from volcanic eruptions of liquid water or solid ice to tectonic deformation but definitive high resolution morphological evidence has been lacking here we report digital elevation models of parts of the surface of ganymede derived from stereo pairs combining data from the voyager and galileo spacecraft which reveal bright smooth terrains that lie at roughly constant elevations 100 to 1 000 metres below the surrounding rougher terrains these topographic data together with new images that show fine scale embayment and burial of older features indicate that the smooth terrains were formed by flooding of shallow structural troughs by low viscosity water ice lavas the oldest and most deformed areas the reticulate terrains in general have the highest relative elevations whereas units of the most common resurfaced type the grooved terrain lie at elevations between those of the smooth and reticulate terrains bright terrain which accounts for some two thirds of the surface probably results from a continuum of processes including crustal rifting shallow flooding and groove formation volcanism plays an integral role in these processes and is consistent with partial melting of ganymede s interior

the distribution of bright and dark material on ganymede in relationship to surface elevation and slopes abstract the unique high resolution digital terrain data set available for ganymede s uruk sulcus area and galileo regio is analyzed by quantitative image analysis techniques to identify relationships between surface brightness elevation and slopes broad and narrow ridges and grooves of the uruk sulcus terrain model are found to be aligned with bright and dark lineament patterns visible in images these prominent lineaments represent areas covered by bright and dark albedo material not effects of photometric shading there is a strong correlation between material locations and elevation bright material is found on topographic highs whereas dark material is located in depressions the relative abundance of the dark material increases with lower elevation in galileo regio we find that bright material is also located on slopes facing north we suggest that the bright material in uruk sulcus and galileo regio was emplaced or exposed during or after formation of the terrain in its present location whereas the dark material was eroded and redistributed down slope effects of net solar illumination may play a role in the peculiar azimuthal distribution of bright and dark material on slopes

dark terrain on ganymede geological mapping and interpretation of galileo regio at high resolution abstract during its first two encounters with ganymede the galileo spacecraft obtained images of a 16 500 km 2 portion of galileo regio a large expanse of dark terrain at high resolution 76 86 m pixel through mapping of the g1 and g2 target sites within galileo regio we are able to characterize geological units based on their morphology and relative albedo we find three generally low albedo units an intermediate albedo plains unit a lower albedo plains unit and the lowest albedo unit which is found on furrow and crater floors we also find high albedo units which include crater rims furrow rims and isolated knobs and massifs other features include an intermediate albedo lobate feature interpreted to be a palimpsest and a hummocky unit interpreted to be impact ejecta several processes are interpreted to have occurred within galileo regio these include tectonic deformation mass wasting sublimation resurfacing by impact ejecta and possibly cryovolcanism and isostatic adjustment we observe that the nw se trending furrows lakhmu fossae in galileo regio are degraded and are crosscut by the younger n s trending furrows zu fossae we also find several other tectonic features which may be minor faults or fractures related to one or other of these systems through mapping and crater size frequency distributions we are able to propose a stratigraphy for the galileo regio target site the oldest features in the area are high albedo knobs and massifs which are interpreted to be remnants of early impact related features and furrow rims these may have formed at approximately the same time as the intermediate and low albedo plains units and the furrow systems the lowest albedo unit of furrow floors probably subsequently evolved through sublimation and mass wasting much of the northeast portion of the target area was subsequently obscured by one of the youngest units ejecta from an impact just to the north we use our mapping of the high resolution images of galileo regio to evaluate three end member models for the formation of dark terrain 1 the crust is dark throughout 2 material on the surface is the result of a low albedo cryovolcanic layer over a higher albedo crust and 3 dark material is distributed in small quantities throughout the crust and geological processes have acted to concentrate low albedo material on the surface although it is possible that elements of more than one of these models are present within the dark terrain we find that the third model that of a thin veneer of low albedo material best fits observations of galileo regio

mass anomalies on ganymede abstract radio doppler data generated with nasa s galileo spacecraft during its second encounter with jupiter s moon ganymede are used to infer the locations and magnitudes of mass anomalies on ganymede we construct models for both surface and buried anomalies with only one flyby and no global coverage a solution for mass anomalies cannot be uniquely determined however we are able to constrain acceptable solutions for mass anomalies to four broad regions a near polar region and three that are roughly equatorial if the mass anomalies are constrained to lie at the surface the centers of the regions are located near the coordinates 77 n 333 w 36 n 0 w 33 n 130 w and 7 n 194 w if the mass anomalies are located at the deep ice rock interface 800 km below the surface the regions centers are approximately 65 n 17 w 32 n 30 w 37 n 175 w and 15 n 211 w for both models the regions are up to a few thousand kilometers across the magnitude of mass anomalies on the surface is on the order of 10 17 kg mass anomalies at the ice rock interface are on average no more than an order of magnitude larger 10 18 kg there are two positive and two negative mass anomalies in both the surface and ice rock interface models one of the positive mass anomalies at the surface is associated with galileo regio the other positive surface mass anomaly is located at high northern latitudes with no obvious geological association negative surface mass anomalies lie near uruk sulcus and between perrine regio and barnard regio near sicyan sulcus and phrygia sulcus the locations of the ice rock interface mass anomalies lie approximately radially below the surface anomalies positive mass anomalies at the surface could be associated with the silicate rich ice or accumulated silicate layers of the dark regions negative mass anomalies at the surface could be associated with the relatively clean low lying ice of sulci alternatively ganymede s mass anomalies could be associated with the topography or other mass concentrations at the deep ice rock interface

petrology of the unbrecciated eucrites abstract twenty nine unbrecciated eucrites have been thoroughly characterized in terms of the petrologic factors that affect their spectra such as mineral chemistry modal adundances grain sizes and textures we have conducted a combined petrologic and spectral study designed to provide insight into the petrogenesis of the basaltic crust of vesta and the variety of rock types that exist within it as well as aid in the petrologic interpretation of spectra to be collected by the dawn orbiting spacecraft this paper details the petrology part of the study unbrecciated eucrite samples were selected to avoid the complications of lithologic mixing in the accompanying spectral study a wide variety of textural types are seen within the basaltic eucrites encompassing quenched coarse grained and granoblastic samples zoned pyroxenes in eucrites and those that preserve a history of initial rapid cooling are rare nearly all eucrite samples have been thermally metamorphosed and would commonly be classified as equilibrated however this term reflects only the quadrilateral mg fe and ca compositions of pyroxenes and considerable variations are seen within the minor elements al ti and cr in pyroxenes as well as plagioclase compositions determination of both pyroxene and plagioclase compositions together with pyroxene geothermometry provides a better estimate for the relative degree of thermal metamorphism a eucrite has experienced the petrologic differences observed here might allow different eucrites to be distinguished spectrally this is especially true for the varying pyroxene compositions as the spectra of eucrites are dominated by absorption features attributed to pyroxene

reorientation of icy satellites by impact basins 1 large impact basins are present on many of the icy satellites of the outer solar system assuming that their present day topography is uncompensated such basins can cause significant poleward reorientations for slow rotating satellites this reorientation may have been accompanied by transient large amplitude wobble the largest basins on tethys rhea and titania are predicted to have caused reorientations of roughly 4 7 and 12 respectively resulting in global tectonic stresses up to 0 5 mpa the potential anomalies associated with the basins can be up to one third of those expected for a hydrostatic tidally and rotationally deformed body and may complicate interpretation of the satellite interior structure pluto and charon because of their slow rotation are also likely to have undergone reorientation of 10 20 if they possess impact basins of comparable sizes to those of the saturnian satellites

determination of planetary basalt parentage a simple technique using the electron microprobe many basaltic meteorites are being discovered in old and new meteorite suites including those from cold deserts e g antarctica and hot desert environments it is important to establish the specific planetary body source proven techniques for establishing planetary parentage include stable isotopic signatures especially oxygen certain elemental ratios in bulk samples and certain elemental ratios in specific minerals some of these techniques are expensive require considerable sample preparation and are adversely affected by weathering processes on the parent body or on earth we have been seeking key major and minor elemental ratios in pyroxene olivine and feldspar that can be measured by the electron microprobe on standard thin sections these ratios may be preserved in unweathered portions of mineral grains and thus see through weathering processes in addition if the sample is too small to provide a representative bulk composition it may still have key information recorded in individual minerals we have found that some of the most useful chemical parameters are fe mn atomic in olivine or pyroxene and the percent anorthite an in plagioclase solid solutions a plot of fe mn in pyroxene and or olivine verses an defines compositional fields that are significantly different for earth mars moon 4 vesta and the angrite parent body this method may be especially powerful when combined with oxygen isotope data

grooved terrain on ganymede first results from galileo high resolution imaging abstract high resolution galileo imaging has provided important insight into the origin and evolution of grooved terrain on ganymede the uruk sulcus target site was the first imaged at high resolution and considerations of resolution viewing geometry low image compression and complementary stereo imaging make this region extremely informative contrast variations in these low incidence angle images are extreme and give the visual impression of topographic shading however photometric analysis shows that the scene must owe its character to albedo variations a close correlation of albedo variations to topography is demonstrated by limited stereo coverage allowing extrapolation of the observed brightness and topographic relationships to the rest of the imaged area distinct geological units are apparent across the region and ridges and grooves are ubiquitous within these units the stratigraphically lowest and most heavily cratered units lineated grooved terrain generally show morphologies indicative of horst and graben style normal faulting the stratigraphically highest groove lanes parallel ridged terrain exhibit ridges of roughly triangular cross section suggesting that tilt block style normal faulting has shaped them these extensional tectonic models are supported by crosscutting relationships at the margins of groove lanes thus a change in tectonic style with time is suggested in the uruk sulcus region varying from horst and graben faulting for the oldest grooved terrain units to tilt block normal faulting for the latest units the morphologies and geometries of some stratigraphically high units indicate that a strike slip component of deformation has played an important role in shaping this region of grooved terrain the most recent tectonic episode is interpreted as right lateral transtension with its tectonic pattern of two contemporaneous structural orientations superimposed on older units of grooved terrain there is little direct evidence for cryovolcanic resurfacing in the uruk sulcus region instead tectonism appears to be the dominant geological process that has shaped the terrain a broad wavelength of deformation is indicated corresponding to the voyager observed topography and may be the result of ductile necking of the lithosphere while a finer scale of deformation probably reflects faulting of the brittle near surface the results here form a basis against which other galileo grooved terrain observations can be compared

ice covered water volcanism on ganymede eruption of liquid h2o magmas along extensional fractures and graben bounding normal faults may have played a critical role in the development of ganymede s grooved terrain the resurfacing potential of a water magma is dependent on a variety of factors including the areal extent of the source region the rate of discharge the thickness of the flow and the time that it takes the flow to completely freeze to its base in this paper the thermal evolution of such a flow is considered in detail the minimum unfrozen lifetime of a 5 m flow is approximately 12 5 days while a 10 m flow would survive for at least 50 days heating resulting from factional head loss could reasonably extend these lifetimes by 50 or more with a discharge rate of the order of 1 10 km3 d 1 an individual volcanic water flow could flood an area of 104 km2 before freezing as the flow solidifies its volume will increase thus lifting and arching its protective ice cover extensional fractures may then develop in the ice subparallel to the graben walls these fractures could result in grooves directly given a sufficiently thick 1 km flow or they may simply act to concentrate various tectonic forces that could initiate groove producing faults

titan s gravity field and interior structure after cassini since its arrival at saturn in 2004 cassini performed nine flybys devoted to the determination of titan s gravity field and its tidal variations here we present an updated gravity solution based on the final data set collected during the gravity dedicated passes before cassini s plunge into saturn s atmosphere the data set includes an additional flyby t110 march 2015 primarily devoted to imaging titan s north polar lakes carried out with the low gain antenna this flyby was particularly valuable because the closest approach occurred at a high latitude 75 n over an area not previously sampled previously published gravity results iess et al 2012 indicated that titan is subject to large eccentricity tides in response to the time varying perturbing potential exerted by saturn the magnitude of the response quadrupole field expressed in the tidal love number k 2 was used to infer the existence of an internal ocean the new gravity field determination provides an improved estimate of k 2 of about 0 62 accurate to a level of a few percent the value is higher than the simplest models of titan suggest and the interpretation is unclear possibilities include a high density ocean as high as 1300 kg m 3 a partially viscous response of the deeper region or a dynamic contribution to the tidal response the new solution includes higher degree and order harmonic coefficients up to 5 and offers an improved map of gravity anomalies the geoid is poorly correlated with the topography implying strong compensation in addition the updated geoid and its associated uncertainty could be used to refine the gravity altimetry correlation analysis and for improved interpretation of radar altimetric data

geology and mapping of dark terrain on ganymede and implications for grooved terrain formation geological mapping of regional and high resolution galileo images reveals a variety of units and structures within ganymede s dark terrain we have made a detailed study of areas within galileo marius and nicholson regiones in order to investigate the style of tectonic deformation experienced by dark terrain adjacent to swaths of grooved terrain dark terrain appears to become fractured as a precursor to grooved terrain formation in places dark fractured swaths are recognized which have similar characteristics to brighter grooved terrain swaths tectonic deformation may be but is not always focused through preexisting weaknesses caused by impact craters and furrows a prominent groove lane anshar sulcus is inferred to have formed by the process of hanging wall rollover accompanied by a small amount of right lateral horizontal shear offset resulting from ne sw extension

geophysical implications of the long wavelength topography of rhea 1 we use limb profiles to investigate the long wavelength topography and topographic variance spectrum of rhea one dimensional variance spectra show a break in slope at a wavelength of 300 km a similar effect is seen on the moon and may be a signature of an elastic lithosphere having a thickness te 10 km the implied heat flux is 15 mw m 2 much higher than can be explained by radiogenic heating we use the 1 d spectral behavior to constrain our solution for the long wavelength global topography of rhea the degree 3 topography is large enough if uncompensated to contaminate estimates of the degree 2 gravity using existing flyby data current models of rhea internal structures which rely on these degree 2 estimates may thus be inaccurate illustrating the need to acquire further rhea gravity data

the south african polymict eucrite macibini the polymict eucrite macibini is a fragmental breccia predominantly composed of eucritic materials with minor proportions maximum 2 vol of diogenitic material hence it is intermediate between the yamato 74159 type polymict eucrites which contain negligible amounts of magnesian orthopyroxene and the howardites the present study provides mineralogical and bulk compositional data for the meteorite breccia and for six clasts these clasts include both volcanic and igneous rocks and a variety of impact generated rocks a broad range of degrees of postcrystallization metamorphism affected these materials before the final aggregation of the breccia clast a is a fragment of unequilibrated eucrite with subophitic texture the edges of the zoned pyroxenes in this clast are composed of a host of fe rich augite containing vermicules blebs and lamellae composed of a mixture of fe rich olivine and silica similar features occur as fragments in lunar breccias and are attributed by some workers to the breakdown of pyroxferroite an fe rich pyroxenoid however textures and compositions of these augite olivine silica intergrowths in clast a suggest that in this case they are the result of decomposition in a series of steps of fe rich subcalcic augite among the fragments of impact generated material in macibini is clast 2 an earlier formed clastic breccia that was lithified before being broken apart and included in the meteorite breccia clast 3 is an impact melt breccia that is composed of rock and mineral fragments in a devitrified groundmass clast c is also an impact melt breccia that has a coarser grained hornfelsic groundmass that resulted from extensive metamorphism after formation

constraints on the location magnitude and dimensions of ganymede s mass anomalies abstract previously radio doppler data generated with nasa s galileo spacecraft during its second encounter with jupiter s moon ganymede were used to infer the locations and magnitudes of mass anomalies on ganymede using point mass models however the point mass solutions do not provide the vertical and horizontal extent of the anomalous mass concentrations here we provide the results of a new study using spherical cap disks to model ganymede s mass anomalies the spherical cap disk models not only provide the locations and magnitudes of the mass anomalies but also their vertical and horizontal dimensions the new models show that three disks a positive mass located at 53 0 n 127 0 w and two negative masses located at 22 0 n 87 0 w and 49 0 n 219 0 w can explain the data the magnitudes of the mass anomalies are on the order of 10 18 kg the diameters of the anomalies are a few thousand kilometers the positive anomaly is about 100 meters thick and both negative anomalies have a thickness of less than a kilometer we use the additional information provided by the disk models to investigate the viability of mass anomalies at ganymede s surface by comparing the diameters of the anomalies to the sizes of regiones and sulci and the anomalies thicknesses to accumulated layers of rock and clean ice on the surface we find that the dimensions of the mass anomalies could be explained by concentrations of rock in the regio and rock free ice in the sulci these results confirm that mass anomalies may reside on or near ganymede s surface and that positive mass anomalies are contained within areas of dark terrain and negative mass anomalies within bright terrain

a review of the origins of subparallel ridges and troughs generalized morphological predictions from terrestrial models the morphologies of ridges and troughs on earth and the processes involved in their formation are reviewed for application to sets of subparallel ridges and troughs on outer planet satellites we consider tension fracturing normal faulting thrust faulting buckle folding strike slip tectonism fissure eruption wall diapirism surface folding of a flow and near surface laccolithic intrusion the landform characteristics and geologic associations predicted of each process are generalized to be independent of planet specific parameters we find that the combinations of landforms derived from each process are unique making each distinguishable in the idealized case morphological parameters most diagnostic of formational process are ridge and trough cross sectional shape termination style and incipient character the characteristics described are useful in constraining the origin of ridge and trough terrains observed in voyager images and will aid in analysis of high resolution images from the galileo and cassini spacecraft

on the resurfacing of ganymede by liquid water volcanism abstract a long popular model for producing ganymede s bright terrain involves flooding of low lying graben with liquid water slush or warm soft ice the model suffers from major problems however including the absence of obvious near surface heat sources the negative buoyancy of liquid water and the lack of a mechanism for confining the flows to graben floors we present new models for cryovolcanic resurfacing to overcome these difficulties tidal heating within an ancient laplace like orbital resonance showman and malhotra 1997 icarus 127 93 showman et al 1997 icarus 129 367 provides a plausible heat source and could allow partial melting to occur as shallow as 5 10 km depth our favored mechanism for delivering this water to the surface invokes the fact that topography such as a global set of graben causes subsurface pressure gradients that can pump water or slush upward onto the floors of topographic lows graben despite the negative buoyancy of the liquid these eruptions can occur only within the topographic lows furthermore as the low areas become full the pressure gradients disappear and the resurfacing ceases this provides an explanation for the observed straight dark bright terrain boundaries water cannot overflow the graben so resurfacing rarely embays craters or other rough topography pure liquid water can be pumped to the surface from only 5 10 km depth but macroscopic bodies of slush ascending within fractures can reach the surface from much greater depths due to the smaller negative buoyancy of slush a challenge for these models is the short predicted gravitational relaxation timescale of topographic features at high heat flows the resurfacing must occur before the graben topography disappears we also evaluate alternate resurfacing mechanisms such as pumping of liquid water to the surface by thermal expansion stresses and buoyant rise of water through a silicate contaminated crust that is denser than liquid water and conclude that they are unlikely to explain ganymede s bright terrain

geophysical implications of the long wavelength topography of the saturnian satellites 1 we use limb profiles to quantify the long wavelength topography of the saturnian satellites the degree 2 shapes of mimas enceladus and tethys are not consistent with hydrostatic equilibrium we derive 2 d topographic maps out to spherical harmonic degree 8 there is a good correlation with topography derived from stereo techniques if uncompensated topography at degree 3 and higher is large enough to be detectable during close spacecraft flybys if not properly accounted for this topography may bias estimates of a satellite s degree 2 gravity coefficients which are used to determine the moment of inertia we also derive a one dimensional variance spectrum a measure of how roughness varies with wavelength for each body the short wavelength spectral slope is 2t o 2 5 similar to silicate bodies however unlike the terrestrial planets each satellite spectrum shows a reduction in slope at longer wavelengths if this break in slope is due to a transition from flexural to isostatic support the globally averaged elastic thickness te of each satellite may be derived we obtain te values of 5 km 1 5 5 km 5 km and 5 km for tethys dione rhea and iapetus respectively for europa we obtain te 1 5 km these estimates are generally consistent with estimates made using other techniques for enceladus intermediate wavelengths imply te 0 5 km but the variance spectrum at wavelengths greater than 150 km is probably influenced by long wavelength processes such as convection or shell thickness variations impact cratering may also play a role in determining the variance spectra of some bodies citation nimmo f b g bills and p c thomas 2011 geophysical implications of the long wavelength topography of the saturnian satellites j geophys res 116 e11001 doi 10 1029 2011je003835

mineral chemistry and the petrogenesis of eucrites ii cumulate eucrites abstract we carried out an ion microprobe study of rees and other selected trace and minor element concentrations in orthopyroxene augite lamellae and plagioclase of two cumulate eucrites moama and moore county in order to reevaluate the relationships between cumulate and noncumulate eucrites and among cumulate eucrites pyroxene and plagioclase in these two meteorites are more homogeneous in major minor and trace elements than in noncumulate eucrites and trace and minor element concentrations in moore county are higher than in moama although subsolidus equilibration erased and original igneous zoning it did not affect the ree patterns of these minerals both pigeonite and plagioclase of moama and moore county have higher lree hree ratios than those phases in noncumulate eucrites this indicates that cumulate eucrites derived from melts with fractionated ree patterns and thus are not related to noncumulate eucrites in addition the inconsistency between degrees of fractional crystallization deduced from major and trace elements and the differences of lree hree ratios recorded in pigeonite and plagioclase also suggest that moama and moore county did not form in the same fractional crystallization sequence this study confirms earlier observations and conclusions of ma and schmitt 1979 and poses problems for prevalent models

discovery of mass anomalies on ganymede we present the discovery of mass anomalies on ganymede jupiter s third and largest galilean satellite this discovery is surprising for such a large icy satellite we used the radio doppler data generated with the galileo spacecraft during its second encounter with ganymede on 6 september 1996 to model the mass anomalies two surface mass anomalies one a positive mass at high latitude and the other a negative mass at low latitude can explain the data there are no obvious geological features that can be identified with the anomalies

diapir induced reorientation of saturn s moon enceladus the recent discovery of active water venting from the surface of saturn s icy moon enceladus has caused a ripple of excitement as it suggests the possibility of subsurface liquid water geologically enceladus poses problems one the reason why the hotspot of geological activity is centred precisely on the south pole has been tackled by francis nimmo and robert t pappalardo they identify reorientation of enceladus s rotation axis as the likely cause and an upwelling of low density material to the surface as the cause of that reorientation comparison of the distribution of impact craters on the leading and trailing hemispheres will be a good test of the reorientation part of the theory enceladus is a small icy satellite of saturn its south polar region consists of young tectonically deformed terrain and has an anomalously high heat flux1 2 this heat flux is probably due to localized tidal dissipation within either the ice shell3 or the underlying silicate core4 the surface deformation is plausibly due to upwelling of low density material diapirism5 as a result of this tidal heating here we show that the current polar location of the hotspot can be explained by reorientation of the satellite s rotation axis because of the presence of a low density diapir if the diapir is in the ice shell then the shell must be relatively thick and maintain significant rigidity elastic thickness greater than 0 5 km if the diapir is in the silicate core then enceladus cannot possess a global subsurface ocean because the core must be coupled to the overlying ice for reorientation to occur the reorientation generates large 10 mpa tectonic stress patterns6 that are compatible with the observed deformation of the south polar region2 we predict that the distribution of impact craters on the surface will not show the usual leading hemisphere trailing hemisphere asymmetry a low density diapir also yields a potentially observable negative gravity anomaly

local lunar gravity field analysis over the south pole aitken basin from selene farside tracking data 1 we present a method with which we determined the local lunar gravity field model over the south pole aitken spa basin on the farside of the moon by estimating adjustments to a global lunar gravity field model using selene tracking data our adjustments are expressed in localized functions concentrated over the spa region in a spherical cap with a radius of 45 centered at 191 1 e 53 2 s and the resolution is equivalent to a 150th degree and order spherical harmonics expansion the new solution over spa was used in several applications of geophysical analysis it shows an increased correlation with high resolution lunar topography in the frequency band l 40 70 and admittance values are slightly different and more leveled when compared to other global gravity field models using the same data the adjustments expressed in free air anomalies and differences in bouguer anomalies between the local solution and the a priori global solution correlate with topographic surface features the moho structure beneath the spa basin is slightly modified in our solution most notably at the southern rim of the apollo basin and around the zeeman crater