global distribution of large lunar craters implications for resurfacing and impactor populations by using high resolution altimetric measurements of the moon we produced a catalog of all impact craters 20 kilometers in diameter on the lunar surface and analyzed their distribution and population characteristics the most densely cratered portion of the highlands reached a state of saturation equilibrium large impact events such as orientale basin locally modified the prebasin crater population to 2 basin radii from the basin center basins such as imbrium orientale and nectaris which are important stratigraphic markers in lunar history are temporally distinguishable on the basis of crater statistics the characteristics of pre and postmare crater populations support the hypothesis that there were two populations of impactors in early solar system history and that the transition occurred near the time of the orientale basin event

summary of the results from the lunar orbiter laser altimeter after seven years in lunar orbit in june 2009 the lunar reconnaissance orbiter lro spacecraft was launched to the moon the payload consists of 7 science instruments selected to characterize sites for future robotic and human missions among them the lunar orbiter laser altimeter lola was designed to obtain altimetry surface roughness and reflectance measurements the primary phase of lunar exploration lasted one year following a 3 month commissioning phase on completion of its exploration objectives the lro mission transitioned to a science mission after 7 years in lunar orbit the lola instrument continues to map the lunar surface the lola dataset is one of the foundational datasets acquired by the various lro instruments lola provided a high accuracy global geodetic reference frame to which past present and future lunar observations can be referenced it also obtained high resolution and accurate global topography that were used to determine regions in permanent shadow at the lunar poles lola further contributed to the study of polar volatiles through its unique measurement of surface brightness at zero phase which revealed anomalies in several polar craters that may indicate the presence of water ice in this paper we describe the many lola accomplishments to date and its contribution to lunar and planetary science

global distribution of lunar impact melt flows abstract in this study we analyzed the distribution and properties of 146 craters with impact melt deposits exterior to their rims many of these craters were only recently discovered due to their unusual radar properties in the near global mini rf data set we find that most craters with exterior deposits of impact melt are small 20 km and that the smallest craters have the longest melt flows relative to their size in addition exterior deposits of impact melt are more common in the highlands than the mare this may be the result of differing target properties in the highlands and mare the difference in titanium content or the greater variation of topography in the highlands we find that 80 of complex craters and 60 of simple craters have melt directions that are coincident or nearly coincident with the lowest point in their rim implying that pre existing topography plays a dominant role in melt emplacement this is likely due to movement during crater modification complex craters or breached crater rims simple craters we also find that impact melt flows have very high circular polarization ratios compared to other features on the moon this suggests that their surfaces are some of the roughest material on the moon at the centimeter to decimeter scale even though they appear smooth at the meter scale

the timing of martian valley network activity constraints from buffered crater counting abstract valley networks concentrations of dendritic channels that often suggest widespread pluvial and fluvial activity have been cited as indicators that the climate of mars differed significantly in the past from the present hyperarid cold desert conditions some researchers suggest that the change in climate was abrupt while others favor a much more gradual transition thus the precise timing of valley network formation is critical to understanding the climate history on mars we examine thirty valley network incised regions on mars including both cratered upland valley networks and those outside the uplands and apply a buffered crater counting technique to directly constrain when valley network formation occurred the crater populations that we derive using this approach allow assessment of the timing of the last activity in a valley network independent of the mapping of specific geological units from these measurements we find that valley networks cluster into two subdivisions in terms characteristics and age 1 valley network activity in the cratered highlands has an average cessation age at the noachian hesperian boundary and all valleys that we crater counted are early hesperian or older no evidence is found for valley networks in the cratered uplands of late hesperian or amazonian age the timing of the cessation of cratered upland valley network activity at the noachian hesperian boundary also corresponds to a decline in the intensity of large crater formation and degradation and to the apparent end of phyllosilicate type weathering 2 a few valley network incised regions formed outside of the cratered uplands on volcanic edifices in association with younger impact craters and on the rim of valles marineris we applied our buffered crater counting technique to four such valleys on the volcanoes ceraunius tholus hecates tholus and alba patera and on the rim of echus chasma and find that each has distinctive and different late hesperian or early amazonian ages indicating that valley networks formed from time to time in the post noachian period unlike the cratered upland valley networks these isolated occurrences are very local and have been interpreted to represent local conditions e g snowpack melted during periods of intrusive volcanic activity in contrast to a gradual cessation in the formation of valley networks proposed by some workers our new buffered crater counting results indicate a relatively abrupt cessation in the formation of the widespread cratered upland valley networks at approximately the end of the noachian followed only by episodic and very localized valley network formation in later mars history very likely due to specific conditions e g local magmatic heating these valley network ages and correlations are thus consistent with a major change in the near surface aqueous environment on mars at approximately the noachian hesperian boundary the noachian environment supported surface running water and fluvial erosion across mars in the cratered uplands enhanced crater degradation and a weathering environment favoring the formation of phyllosilicates the hesperian amazonian environment was more similar to the hyperarid cold desert of today with valley networks forming only extremely rarely and confined to localized special conditions sources of water for these latter occurrences are likely to be related to periodic mobilization and equatorward migration of polar volatiles due to variations in spin axis orbital parameters and to periodic catastrophic emergence of groundwater

new observational evidence of global seismic effects of basin forming impacts on the moon from lunar reconnaissance orbiter lunar orbiter laser altimeter data 1 new maps of kilometer scale topographic roughness and concavity of the moon reveal a very distinctive roughness signature of the proximal ejecta deposits of the orientale basin the hevelius formation no other lunar impact basin even the just preceding imbrium basin is characterized by this type of signature although most have similar types of ejecta units and secondary crater structures the preservation of this distinctive signature and its lack in basins formed prior to orientale is interpreted to be the result of seismically induced smoothing caused by this latest major basin forming event intense seismic waves accompanying the orientale basin forming event preceded the emplacement of its ejecta in time and operated to shake and smooth steep and rough topography associated with earlier basin deposits such as imbrium orientale ejecta emplaced immediately following the passage of the seismic waves formed the distinctive roughness signature that has been preserved for almost 4 billion years

effects of geology and human activity on the dynamics of salt water intrusion in three coastal aquifers in southern spain mathematical modelling of salt water intrusion processes in three aquifers on the southern coast of spain rio verde rio velez and castell de ferro reveals that although all three systems are subject to the same climate and seasonal over exploitation geological and human factors have very different effects on the dynamics of contamination in the rio verde aquifer the most important influence is the high volume of extractions occurring during the dry season in rio velez the intrusion is strongly controlled by infiltration of water from the river to the aquifer and in the castell de ferro system an intensely karstified carbonate massif lying in contact with both the sea water and the detrital aquifer represents the main entrance point for influx of sea water and subsequent washing of the aquifer we have undertaken a mathematical simulation of various possible measures to counteract intrusion according to the specific characteristics of the process in each aquifer these measures include artificial recharge use of natural recharge from the river as a hydraulic barrier and the construction of a low permeability barrier

upward groundwater flow in boils as the dominant mechanism of salinization in deep polders the netherlands as upward seepage of saline groundwater from the upper aquifer is leading to surface water salinization of deep polders in the netherlands we monitored the processes involved in the noordplas polder a typical deep polder our results show three types of seepage 1 diffuse seepage through the holocene confining layer 2 seepage through paleochannel belts in the holocene layer and 3 intense seepage via localized boils they differ with regard to seepage flux chloride concentration and their location in the polder thus their contributions to surface water salinization also differ permeable sandy paleochannel belts cut through the lower part of the holocene layer resulting in higher seepage fluxes than the diffuse seepage through the holocene layer where there are no paleochannels the average chloride concentration of paleochannel seepage is about 600 mg l which is sixfold higher than the average concentration of diffuse seepage the highest seepage fluxes and chloride concentrations are found at boils which are small vents in the holocene layer through which groundwater preferentially discharges at high velocities this results in upconing of deeper and more saline groundwater which produces an average chloride concentration of 1100 mg l despite the fact that seepage fluxes are difficult to measure we were able to calculate that boils contribute more than 50 of the total chloride load entering the noordplas polder and they therefore form the dominant salinization pathway

unravelling the mystery of lunar anomalous craters using radar and infrared observations in miniature radio frequency mini rf radar images anomalous craters are those having a high circular polarization ratio cpr in their interior but not exterior to their rims previous studies found that most cpr anomalous craters contain permanently shadowed regions psrs and that their population is overabundant in the polar regions however there is considerable controversy in the interpretation of these signals both water ice deposits and rocks surface roughness have been proposed as the source of the elevated cpr values to resolve this controversy we have systematically analyzed 4000 impact craters with diameters between 2 5 and 24 km in the mini rf radar image and diviner rock abundance ra map we first constructed two controlled orthorectified global mosaics using 6818 tracks of mini rf raw data and then analyzed the correlations between radar cpr and surface slope rock abundance and depth diameter ratios of impact craters our results show that cpr anomalous craters are distributed relatively uniformly across the lunar surface with no apparent difference in cpr between the polar potentially icy and non polar not icy craters most cpr anomalous craters are relatively young with a large depth diameter ratio and they actually represent an intermediate stage of crater evolution comparison with a two component radar scattering model suggests that rocks and surface roughness are major contributors to the observed cpr values using craters of 4 7 22 km in diameter with known ages we find that craters spend up to 120 ma with a high exterior ra and 3 ga in the cpr anomalous phase

lunar crater identification via deep learning abstract crater counting on the moon and other bodies is crucial to constrain the dynamical history of the solar system this has traditionally been done by visual inspection of images thus limiting the scope efficiency and or accuracy of retrieval in this paper we demonstrate the viability of using convolutional neural networks cnns to determine the positions and sizes of craters from lunar digital elevation maps dems we recover 92 of craters from the human generated test set and almost double the total number of crater detections of these new craters 15 are smaller in diameter than the minimum crater size in the ground truth dataset our median fractional longitude latitude and radius errors are 11 or less representing good agreement with the human generated datasets from a manual inspection of 361 new craters we estimate the false positive rate of new craters to be 11 moreover our moon trained cnn performs well when tested on dem images of mercury detecting a large fraction of craters in each map our results suggest that deep learning will be a useful tool for rapidly and automatically extracting craters on various solar system bodies we make our code and data publicly available at https github com silburt deepmoon git and https doi org 10 5281 zenodo 1133969

lunar crater detection based on terrain analysis and mathematical morphology methods using digital elevation models lunar impact craters are the most typical geomorphic feature on the moon and are of great importance in studies of lunar terrain features this paper presents a crater detection algorithm cda that is based on terrain analysis and mathematical morphology methods the proposed cda is applied to digital elevation models dems to identify the boundaries of impact craters the topographic and morphological characteristics of impact craters are discussed and detailed steps are presented to detect different types of craters such as dispersal craters connective craters and con craters the dem from the lunar reconnaissance orbiter which has a resolution of 100 m is used to verify the proposed cda the results show that the boundaries of impact craters can be detected the results enable increased understanding of surface processes through the characterization of crater morphometry and the use of crater size frequency distributions to estimate the ages of planetary surfaces

saline intrusion and refreshening in a multilayer coastal aquifer in the catania plain sicily southern italy dynamics of degradation processes according to the hydrochemical characteristics of groundwaters the catania plain is a large alluvial depression which represents one of the most important hydrogeological units in eastern sicily a detailed hydrochemical and hydrogeological investigation focussed on its north eastern corner has provided new insights into the past and present relationship between freshwater and seawater in shallow and deep aquifers according to hydrochemical data over the last centuries the area has been affected by local variations of the sea level giving rise to sequential processes of re equilibration of the exchangeable complex involving freshwater and seawater in both surficial and deep aquifers these ongoing processes consist in the refreshening of both deep aquifers 500 m from the shoreline and to a lesser extent due to lower freshwater influx shallow aquifers in the former case there is a shift of the groundwater compositions towards the na hco3 type and a significant drop in the salt contents while in the latter case the salt contents do not drop significantly at a distance 500 m from the shoreline the exchangeable complex of deep aquifers is presently subject to salinization according to the temporal variabilities in the hydrochemical data over the period 1995 96 the apparent dualism can be attributed to a general worsening of the current freshwater seawater relationship in deep aquifers this new tendency appears to be related to a sharp increase in water consumption by the local industrial plant which has reversed the natural refreshening tendency giving rise to a new saline intrusion that is particularly severe close to the shoreline

lunar topographic roughness maps from lunar orbiter laser altimeter lola data scale dependence and correlation with geologic features and units we present maps of the topographic roughness of the moon at hectometer and kilometer scales the maps are derived from range profiles obtained by the lunar orbiter laser altimeter lola instrument onboard the lunar reconnaissance orbiter lro spacecraft as roughness measures we used the interquartile range of profile curvature at several baselines from 115 m to 1 8 km and plotted these in a global map format the maps provide a synoptic overview of variations of typical topographic textures and utilize the exceptional ranging precision of the lola instrument we found that hectometer scale roughness poorly correlates with kilometer scale roughness because they reflect different sets of processes and time scales hectometer scale roughness is controlled by regolith accumulation and modification processes and affected by the most recent events primarily geologically recent 1 2 ga meteoritic impacts kilometer scale roughness reflects major geological impact volcanic and tectonic events in earlier geological history young large impact craters are rough and their roughness decreases with age the global roughness maps revealed a few unusually dense clusters of hectometer and decameter size impact craters that differ in their morphology and settings from typical secondary crater clusters and chains the origin of these features is enigmatic the maps can assist in the geological mapping of the lunar maria by revealing contacts between volcanic plain units the global roughness maps also clearly reveal cryptomaria old volcanic plains superposed by younger materials primarily crater and basin ejecta

marine and human activity influences on the groundwater quality of southern korinthos area greece in this paper the groundwater quality of the southern part of korinthos region north east peloponnese is discussed the geology is characterized by a thick sequence of neogene marls alternating with sandstones overlain by superficial quaternary deposits the latter consist of a mixture of loose materials such as conglomerates marly sandstones sands and clay to silty sands the area is crossed by a fault system parallel to the coastline and the quaternary sediments have formed extended tyrrhenian marine terraces two aquifers have been identified in the area the first is unconfined and occurs within the quaternary sediments whereas the other is a deep confined aquifer occurring within the underlying neogene marl series analysis of hydrochemical evolution over the past 30 years has indicated significant deterioration of quality owing to seawater intrusion and nitrate pollution the various sources of pollution have rendered to a large extent shallow groundwater unsuitable not only for potable water supply but also for irrigation purposes however this is not the case for the deeper confined aquifer statistical analysis was used to explore the evolution of salinization during the years 1968 and 1998 in view of the alarming conditions caused by the documented groundwater quality deterioration the need for integrated water resources management is stressed to maintain the socio economic growth of the region studied copyright 2003 john wiley sons ltd

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

ages and stratigraphy of mare basalts in oceanus procellarum mare nubium mare cognitum and mare insularum accurate estimates of mare basalt ages are necessary to place constraints on the duration and the flux of lunar volcanism as well as on the petrogenesis of lunar mare basalts and their relationship to the thermal evolution of the moon we performed new crater size frequency distribution measurements in order to investigate the stratigraphy of mare basalts in oceanus procellarum and related regions such as mare nubium mare cognitum and mare insularum we used high resolution clementine color data to define 86 spectrally homogeneous units within these basins which were then dated with crater counts on lunar orbiter iv images our crater size frequency distribution measurements define mineralogical and spectral surface units and offer significant improvements in accuracy over previous analyses our data show that volcanism in the investigated region was active over a long period of time from 3 93 to 1 2 b y a total of 2 7 b y volumetrically most of the basalts erupted in the late imbrian period between 3 3 and 3 7 b y and we see evidence that numerous units have been resurfaced during the eratosthenian period significantly less basalt was erupted depending on the absolute model ages that one can assign to the lunar chronostratigraphic systems five units might be of copernican age younger basalts are generally exposed in the center of the investigated area that is closer to the volcanic centers of the aristarchus plateau and marius hills older basalts occur preferentially along the northwestern margin of oceanus procellarum and in the southeastern regions of the studied area i e in mare cognitum and mare nubium combining the new data with our previously measured ages for basalts in mare imbrium serenitatis tranquillitatis humorum australe and humboldtianum we find that the period of active volcanism on the moon lasted 2 8 b y from 4 b y to 1 2 b y on the basis of the basalts dated so far which do not yet include the potentially young basalts of mare smythii e g schultz and spudis 1983 we conclude that oceanus procellarum not only exhibits the widest range of ages of all investigated basins but probably also is the location of some of the youngest basalts on the lunar surface

isostatic compensation of the lunar highlands the lunar highlands are isostatically compensated at large horizontal scales but the specific compensation mechanism has been difficult to identify with topographic data from the lunar orbiter laser altimeter and gravity data from the gravity recovery and interior laboratory we investigate support of highland topography poor correlation between crustal density and elevation shows that pratt compensation is not important in the highlands using spectrally weighted admittance we compared observed values of geoid to topography ratio gtr with those predicted by isostatic models observed gtrs are 25 8 7 5 5 7 m km for the nearside highlands and 39 3 5 7 6 2 m km for the farside highlands these values are not consistent with flexural compensation of long wavelength topography or airy isostasy defined under an assumption of equal mass in crustal columns instead the observed gtr values are consistent with models of airy compensation in which isostasy is defined under a requirement of equal pressures at equipotential surfaces at depth the gravity and topography data thus reveal that long wavelength topography on the moon is most likely compensated by variations in crustal thickness implying that highland topography formed early in lunar history before the development of a thick elastic lithosphere

geochemical processes and solute transport at the seawater freshwater interface of a sandy aquifer geochemical processes occurring at a seawater freshwater interface were studied in a shallow coastal siliclastic aquifer containing minor amounts of calcite data were collected from 106 piezometers in a 120 m transect from the coastline and landward in the first 40 m from the coastline a wedge of saltwater is intruding below the freshwater aquifer the aquifer is strongly reduced with mineralization of organic matter by methanogenesis in the freshwater aquifer and sulfate reduction dominating in the most seaward part of the saline aquifer the spatial separation of cations in the aquifer indicated a slow freshening process where ca2 from freshwater displaced the marine cations na and mg2 from the exchanger complex the resulting loss of ca2 from solution decreases the saturation state for calcite and possibly causes calcite dissolution a storm flooding event was recorded where pulses of dense seawater sank through the fresh aquifer as a result the terminal electron accepting process switched from methanogenesis to sulfate reduction the pulses of sinking seawater also triggered cation exchange reactions where ca2 was expelled from the exchanger by seawater na and mg2 the released ca2 is being flushed from the aquifer by groundwater flow and this export of ca2 will in the long term cause decalcification of the sediment the water composition in the aquifer is in a transient state as the result of various processes that operate on different timescales oxidation of organic matter occurs continuously but at a rate decreasing on a geological time scale the freshening of the aquifer operates on the timescale of a few years the episodic flooding and sinking of seawater through the aquifer proceeds in the course of days to weeks but occurs irregularly with years in between

groundwater chemistry patterns in the phreatic aquifer of the central belgian coastal plain the holocene geological evolution of the belgian coastal plain is dominated by a transgression of the north sea silting up of the coastal plain and human intervention impoldering this has led to a typical pattern in groundwater quality which is discussed here for the central part of the coastal plain therefore a database with available groundwater samples is composed water type according to the stuyfzand classification is determined and different hydrosomes and their hydrochemical facies are identified based on this the origin and evolution of the water types is explained using piper plots and geochemical calculations with phreeqc before the impoldering salinising and freshening conditions alternated with a general salinisation of the aquifer after about 3400 bp this results in a dominance of brackish and salt nacl subtypes which are still found in the deeper part of the aquifer the subsequent impoldering resulted in an major freshening of the aquifer leading to nahco3 mghco3 and cahco3 subtypes overall mixing cation exchange carbonate mineral dissolution and oxidation of organic matter are identified as the major processes determining the general water quality the close link between geological evolution water quality and what is still observable today is illustrated with this example of the belgian coastal plain

the fractured moon production and saturation of porosity in the lunar highlands from impact cratering we have analyzed the bouguer anomaly ba of 1200 complex craters in the lunar highlands from gravity recovery and interior laboratory observations the ba of these craters is generally negative though positive ba values are observed particularly for smaller craters crater ba values scale inversely with crater diameter quantifying how larger impacts produce more extensive fracturing and dilatant bulking the bouguer anomaly of craters larger than 93 47 19 km in diameter is independent of crater size indicating that there is a limiting depth to impact generated porosity presumably from pore collapse associated with either overburden pressure or viscous flow impact generated porosity of the bulk lunar crust is likely in a state of equilibrium for craters smaller than 30km in diameter consistent with an 8km thick lunar megaregolith whereas the gravity signature of larger craters is still preserved and provides new insight into the cratering record of even the oldest lunar surfaces

lunar impact basins stratigraphy sequence and ages from superposed impact crater populations measured from lunar orbiter laser altimeter lola data 1 impact basin formation is a fundamental process in the evolution of the moon and records the history of impactors in the early solar system in order to assess the stratigraphy sequence and ages of impact basins and the impactor population as a function of time we have used topography from the lunar orbiter laser altimeter lola on the lunar reconnaissance orbiter lro to measure the superposed impact crater size frequency distributions for 30 lunar basins d 300 km these data generally support the widely used wilhelms sequence of lunar basins although we find significantly higher densities of superposed craters on many lunar basins than derived by wilhelms 50 higher densities our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains the transition from a lunar impact flux dominated by population 1 to population 2 occurred before the mid nectarian this is before the end of the period of rapid cratering and potentially before the end of the hypothesized late heavy bombardment lola derived crater densities also suggest that many pre nectarian basins such as south pole aitken have been cratered to saturation equilibrium finally both crater counts and stratigraphic observations based on lola data are applicable to specific basin stratigraphic problems of interest for example using these data we suggest that serenitatis is older than nectaris and humboldtianum is younger than crisium sample return missions to specific basins can anchor these measurements to a pre imbrian absolute chronology

analysis of the topographic roughness of the moon using the wavelet leaders method and the lunar digital elevation model from the lunar orbiter laser altimeter and selene terrain camera

extent age and resurfacing history of the northern smooth plains on mercury from messenger observations abstract messenger orbital images show that the north polar region of mercury contains smooth plains that occupy 7 of the planetary surface area within the northern smooth plains nsp we identify two crater populations those superposed on the nsp post plains and those partially or entirely embayed buried the existence of the second of these populations is clear evidence for volcanic resurfacing the post plains crater population reveals that the nsp do not exhibit statistically distinguishable subunits on the basis of crater size frequency distributions nor do measures of the areal density of impact craters reveal volcanically resurfaced regions within the nsp these results suggest that the most recent outpouring of volcanic material resurfaced the majority of the region and that this volcanic flooding emplaced the nsp over a relatively short interval of geologic time perhaps 100 my or less stratigraphic embayment relationships within the buried crater population including partial crater flooding and the presence of smaller embayed craters within the filled interiors of larger craters and basins indicate that a minimum of two episodes of volcanic resurfacing occurred from the inferred rim heights of embayed craters we estimate the nsp to be regionally 0 7 1 8 km thick with a minimum volume of volcanic material of 4 10 6 to 10 7 km 3 because of the uncertainty in the impact flux at mercury the absolute model age of the post plains volcanism could be either 3 7 or 2 5 ga depending on the chronology applied

depth slicing of multi receiver emi measurements to enhance the delineation of contrasting subsoil features abstract mobile multi receiver electromagnetic induction sensors provide simultaneous readings of the apparent electrical conductivity eca from overlapping soil volumes therefore small contrasting features can be difficult to identify because they have a limited contribution to the bulk measurement especially if they are present in the subsoil i e beneath the topsoil integrating eca data from simultaneous measurements with multiple coil configurations has the potential to elucidate the variability within the soil profile as it enables modelling the electrical conductivity ec for distinct depth intervals therefore it was our objective to develop a methodology to enhance the delineation of contrasting subsoil features such as in filled gullies and archaeological features we selected a 3 5 ha study site where contrasting features were expected a three layered build up was taken as the initial ec slicing model after varying the interface depths the shallowest and deepest ec depth slice showed a clear minimum of their combined variances at interface depths of 0 36 m which corresponded to the ploughing depth and 0 86 m this implies that the ec depth slice in between these depths contained a demonstrably higher variability a sub area of 0 85 ha was completely excavated to a depth of 0 7 m revealing the subsoil features and the host material an automated edge detection algorithm showed that the ec depth slice was superior to any individual eca measurement for delineating the contrasting subsoil features therefore we concluded that depth slicing by integrating simultaneous eca signals from a multi receiver emi sensor clearly improved the identification of subsoil features

circular polarization ratio characteristics of impact craters from mini rf observations and implications for ice detection at the polar regions of the moon 1 in an attempt to reduce the ambiguity on radar detection of water ice at the permanently shadowed regions near the lunar poles radar echo strength and circular polarization ratio cpr of impact craters are analyzed using the miniature radio frequency mini rf radar data from the lunar reconnaissance orbiter mission eight typical craters among over 70 craters are selected and classified into four categories based on their locations and cpr characteristics polar anomalous polar fresh nonpolar anomalous and nonpolar fresh the influences on cpr caused by surface slope rocks and dielectric constant are analyzed quantitatively using high resolution topography data and optical images a two component mixed model for cpr that consists of a normal surface and a rocky surface is developed to study the effect of rocks that are perched on lunar surface and buried in regolith our analyses show that inner wall of a typical bowl shaped crater can give rise to a change of about 30 in local incidence angle of radar wave which can further result in a cpr difference of about 0 2 there is a strong correlation between mini rf cpr and rock abundance that is obtained from high resolution optical images and predictions from the two component mixed model match well with the observed cprs and the estimated rock abundances statistical results show that there is almost no apparent difference in cpr characteristics between the polar and nonpolar anomalous craters or between the polar and nonpolar fresh craters the enhanced cpr in the interior of anomalous craters is most probably caused by rocks that are perched on lunar surface or buried in regolith instead of ice deposits as suggested in previous studies

hydrogeochemical analysis of salinization processes in the coastal aquifer of oropesa castellon spain the coastal aquifer of oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply the aquifer corresponds geologically to a tectonic depression with plioquaternary fill hydrogeologically this aquifer is detrital with intergranular porosity which receives substantial recharge from adjacent mesozoic aquifers contact with the sea in addition to the presence of cultivated soil requiring extreme exploitation of groundwater frequently give rise to processes of seawater intrusion the present research is an attempt to understand the saltwater intrusion in this aquifer using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process in the case of the oropesa sector groundwater salinization does not appear to be attributable solely to the intrusion of seawater but there are also anomalies related largely to the geology of the sector and its surroundings the type of recharge the hydrodynamic conditions in the specific area etc

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

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

improving the geometry of kaguya extended mission data through refined orbit determination using laser altimetry abstract the japan aerospace exploration agency s jaxa kaguya spacecraft carried a suite of instruments to map the moon and its environment globally during its extended mission the average altitude was 50 km or lower and kaguya science products using these data hence have an increased spatial resolution however the geodetic position quality of these products is much worse than that of those acquired during the primary mission at an altitude of 100 km because of reduced radiometric tracking and frequent thrusting to maintain spacecraft attitude after the loss of momentum wheels we have analyzed the kaguya tracking data using gravity models based on the gravity recovery and interior laboratory grail mission and by making use of a new data type based on laser altimeter data collected by kaguya we adjust the spacecraft orbit such that the altimetry tracks fit a precise topographic basemap based on the lunar reconnaissance orbiter s lro lunar orbiter laser altimeter lola data this results in geodetically accurate orbits tied to the precise lola lro frame whereas previously archived orbits show errors at the level of several kilometers the inclusion of altimetry greatly improves the orbit precision to a level of several tens of meters when altimetry data are not available the combination of grail gravity and radio tracking results in an orbit precision of around several hundreds of meters for the low altitude phase of the extended mission our greatly improved orbits result in better geolocation of the kaguya extended mission data set

the effect of craters on the lunar neutron flux the variation of remotely sensed neutron count rates is measured as a function of cratercentric distance using data from the lunar prospector neutron spectrometer the count rate stacked over many craters peaks over the crater center has a minimum near the crater rim and at larger distances it increases to a mean value that is up to 1 lower than the mean count rate observed over the crater a simple model is presented based upon an analytical topographical profile for the stacked craters fitted to data from the lunar orbiter laser altimeter the effect of topography coupled with neutron beaming from the surface largely reproduces the observed count rate profiles however a model that better fits the observations can be found by including the additional freedom to increase the neutron emissivity of the crater area by 0 35 relative to the unperturbed surface it is unclear what might give rise to this effect but it may relate to additional surface roughness in the vicinities of craters the amplitude of the crater related signal in the neutron count rate is small but not too small to demand consideration when inferring water equivalent hydrogen weh weight percentages in polar permanently shaded regions psrs if the small crater wide count rate excess is concentrated into a much smaller psr then it can lead to a large bias in the inferred weh weight percentage for instance it may increase the inferred weh for cabeus crater at the moon s south pole from 1 to 4

redefinition of the crater density and absolute age boundaries for the chronostratigraphic system of mars abstract for the boundaries of each chronostratigraphic epoch on mars we present systematically derived crater size frequencies based on crater counts of geologic referent surfaces and three proposed standard crater size frequency production distributions as defined by a a simple 2 power law b neukum and ivanov c hartmann in turn these crater count values are converted to model absolute ages based on the inferred cratering rate histories we present a new boundary definition for the late hesperian early amazonian transition our fitting of crater size frequency distributions to the chronostratigraphic record of mars permits the assignment of cumulative counts of craters down to 100 m 1 km 2 km 5 km and 16 km diameters to martian epochs due to differences in the standard crater size frequency production distributions a generalized crater density based definition to the chronostratigraphic system cannot be provided for the diameter range used for the boundary definitions the resulting model absolute age fits vary within 1 5 for a given set of production function and chronology model ages crater distributions translated to absolute ages utilizing different curve descriptions can result in absolute age differences exceeding 10

chronology and sources of lunar impact bombardment abstract the moon has suffered intense impact bombardment ending at 3 9 gyr ago and this bombardment probably affected all of the inner solar system basin magnetization signatures and lunar crater size distributions indicate that the last episode of bombardment at about 3 85 gyr ago was less extensive than previously thought we explore the contribution of the primordial mars crosser population to early lunar bombardment we find that mars crosser population initially decays with a 80 myr half life with the long tail of survivors clustering on temporarily non mars crossing orbits between 1 8 and 2 au these survivors decay with half life of about 600 myr and are progenitors of the extant hungaria asteroid group in the same region we estimate the primordial mars crosser population contained about 0 01 0 02 earth masses such initial population is consistent with no lunar basins forming after 3 8 gya and the amount of mass in the hungaria group as they survive longer and in greater numbers than other primordial populations mars crossers are the best candidate for forming the majority of lunar craters and basins including most of the nectarian system however this remnant population cannot produce imbrium and orientale basins which formed too late and are too large to be part of a smooth bombardment we propose that the imbrian basins and craters formed in a discrete event consistent with the basin magnetization signatures and crater size distributions this late impactor shower would be triggered by a collisional disruption of a vesta sized body from this primordial mars crossing population wetherill g w 1975 proc lunar sci conf 6 1539 1561 that was still comparable to the present day asteroid belt a 3 9 gya this tidal disruption lead to a short lived spike in bombardment by non chondritic impactors with a non asteroidal size frequency distribution in agreement with available evidence this body wetherill s object also uniquely matches the constraints for the parent body of mesosiderite meteorites we propose that the present day sources of mesosiderites are multi km sized asteroids residing in the hungaria group that have been implanted there soon after the original disruption of their parent 3 9 gyr ago

numerical modeling of the ejecta distribution and formation of the orientale basin on the moon the formation and structure of the orientale basin on the moon has been extensively studied in the past however estimates of its transient crater size excavated volume and depth and ejecta distribution remain uncertain here we present a new numerical model to reinvestigate the formation and structure of orientale basin and better constrain impact parameters such as impactor size and velocity unlike previous models the observed ejecta distribution and ejecta thickness were used as the primary constraints to estimate transient crater size the best measure of impact energy models were also compared to basin morphology and morphometry and subsurface structures derived from high resolution remote sensing observations and gravity data respectively the best fit model suggests a 100 km diameter impactor with a velocity of 12 km s 1 formed the orientale basin on a relatively cold moon in this impact scenario the transient crater diameter is 400 km or 460 km depending on whether the crater is defined using the diameter of the excavation zone or the diameter of the growing cavity at the time of maximum crater volume respectively the volume of ejecta material is 4 70 106 km3 in agreement with recent estimates of the orientale ejecta blanket thickness from remote sensing studies the model also confirms the remote sensing spectroscopic observations that no mantle material was excavated and deposited at orientale s rim

long term 1960 2010 trends in groundwater contamination and salinization in the ogallala aquifer in texas summary although numerous studies have expounded on depletion of the ogallala aquifer very few researchers have studied groundwater quality therein which relates to the usability of available groundwater resources the objective of this study was to elucidate regional trends in groundwater quality and salinization in the ogallala aquifer underlying 49 counties and two groundwater management areas gma 1 and 2 in texas on a decadal scale between 1960 and 2010 contrasting groundwater quality distinguished gma 1 northern ogallala from gma 2 southern ogallala and shallow wells depth 50 m wells the gma 2 was characterized by pronounced groundwater nitrate no 3 contamination accompanied by elevated levels of sulfate so 4 2 chloride cl and salinity tds marked by an abundance of mixed cation so 4 cl and na cl facies in contrast ca mg hco 3 and ca hco 3 facies prevailed in gma 1 with substantially lower salinization so 4 2 cl and no 3 contamination in shallow wells more abundant in gma 2 about 80 and 32 of observations exceeded the united state environmental protection agency s secondary maximum contaminant level smcl 500 mg l 1 for total dissolved solids tds and mcl 44 mg l 1 for no 3 respectively in the 2000s 2000 2010 with progressive increases in both parameters since the 1960s 1960 1969 majority 60 of the shallow observations since the 1980s 1980 1989 have exceeded the natural background of 11 mg l 1 of no 3 indicating anthropogenic sources the no 3 contamination was more apparent in domestic wells indicating substantial human health risk groundwater salinization in this aquifer resulted from a combination of natural e g upwelling of highly mineralized groundwater from the underlying formations seepage from playas and saline plumes and evaporative enrichment and anthropogenic processes irrigated agriculture and hydrocarbon exploration activities natural processes were largely aggravated by anthropogenic practices such as lowering of hydraulic heads in the ogallala aquifer due to prolonged irrigational pumping inducing cross formational flow from underlying highly mineralized older formations edwards trinity high plains which led to groundwater mixing between the formations and rise in salinity levels in the ogallala aquifer over time

natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the adriatic coast abstract this study characterizes the near shore portion of the shallow coastal aquifer included in the ravenna area northern italy with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity the paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention the influence that multiple natural and anthropogenic factors such as land cover local drainage network and beach erosion have on the presence size and evolution of the freshwater lenses in the aquifer is quantified and discussed the methodology includes multiple seasonal monitoring and sampling campaigns of physical water level salinity and temperature and chemical major cations and anions groundwater parameters results indicate that freshwater lenses where existing are limited in thickness about 1 2 m proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes the pine forest land cover that replaced the typical bush or sand cover intensifies evapotranspiration reducing net infiltration and freshwater storage the cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches whereas a salinization process is ongoing in anthropogenic impacted areas with strongly fragmented dune systems currently the thin freshwater lenses in the shallow ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity the dune beach system however is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization which in turn control the health of the whole coastal ecosystem

re examining the main asteroid belt as the primary source of ancient lunar craters abstract it has been hypothesized that the impactors that created the majority of the observable craters on the ancient lunar highlands were derived from the main asteroid belt in such a way that preserved their size frequency distribution strom r g malhotra r ito t yoshida f kring d a 2005 science 309 1847 1850 a more limited version of this hypothesis dubbed the e belt hypothesis postulates that a destabilized contiguous inner extension of the main asteroid belt produced a bombardment limited to those craters younger than nectaris basin bottke w f vokrouhlick d minton d nesvorn d morbidelli a brasser r simonson b levison h f 2012 nature 485 78 81 we investigate these hypotheses with a monte carlo code called the cratered terrain evolution model ctem which models the topography of a terrain that has experienced bombardment due to an input impactor population we detail our effort to calibrate the code with a human crater counter we also take advantage of recent advances in understanding the scaling relationships between impactor size d i and final crater size d c for basin sized impact craters d c 300 km in order to use large impact basins as a constraint on the ancient impactor population of the moon we find that matching the observed number of lunar highlands craters with d c 100 km requires that the total number of impacting asteroids with d i 10 km be no fewer than 4 10 6 km 2 however this required mass of impactors has d c 64 km craters while not producing a crater larger than imbrium as required by the e belt hypothesis these results suggest that the lunar highlands were unlikely to have been bombarded by a population whose size frequency distribution resembles that of the currently observed main asteroid belt we suggest that the population of impactors that cratered the lunar highlands had a somewhat similar size frequency distribution as the modern main asteroid belt reflecting a similar rocky composition and collisional history but had a smaller ratio of objects capable of producing megabasins compared to objects capable of producing 100 km craters we estimate that the impactor population required to match the lunar highlands had n 5 5 km n 70 km 630 while the modern main asteroid belt ratio is n 5 5 km n 70 km 100

assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower liaohe river plain ne china abstract the lower liaohe river plain lrp is an economically and ecologically important area situated on an alluvial plain where anthropogenic activities are very intensive field investigations were conducted in the lrp and 15 water quality parameters surveyed at 216 wells during september and october of 2009 and 2010 these showed significant variation in the hydrochemistry of groundwater throughout the plain a piper plot was used to identify the major geochemical processes occurring in the entire plain principal components analysis pca was used to identify various underlying natural and anthropogenic processes that created these distinct water types the stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the liaohe river delta five principal components pcs were extracted in terms of pca which can be invoked to explain 82 of the total variance in water quality parameters the pca results can be categorized by five major factors 1 holocene transgression and mixing 2 surface water infiltration 3 multi factor processes 4 rainfall and agricultural fertilizer contamination and 5 geogenic f enrichment this study demonstrates that the great variation of groundwater hydrochemistry in the lrp should be attributed to both natural and anthropogenic processes

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

the global population of large craters on mercury and comparison with the moon 1 we have compiled a near global catalog of impact craters on mercury for diameters 20 km from images obtained during the flybys of the mariner 10 and messenger spacecraft the observed variations in crater density suggest that the smooth plains within and around the caloris basin are the most prominent contiguous comparatively young regions on mercury no other comparably large area appears as young in more heavily cratered terrain even the most densely cratered regions on mercury are deficient in craters between 20 km and 100 km in diameter compared with the moon a result that extends an observation made from mariner 10 images of a smaller fraction of mercury s surface this deficit is interpreted to reflect crustal resurfacing of mercury early in its history most likely by volcanic processes for craters larger than 100 km in diameter the density of craters on mercury in a given size range is similar to that of the moon because such larger craters are less easily removed by volcanic resurfacing we interpret this similarity to be the result of impact saturation effects on both bodies

salinization processes in the unconfined aquifer of bou areg ne morocco a geostatistical geochemical and tomographic study hydrogeological and geochemical data in conjunction with the results of an electrical imaging tomographic survey were examined to determine the main factors and mechanisms controlling the groundwater chemistry and salinity of the unconfined aquifer of bou areg on the mediterranean coast of ne morocco in addition statistical and geochemical interpretation methods were used to identify the distribution of the salinity multivariate statistical analysis cluster and principal component factors revealed the main sources of contamination groups a b and c in the cluster analysis and factors 1 3 factor 1 ce cl k so42 and mg2 factor 2 ca2 hco3 and ph factor 3 no3 represent the signature of seawater intrusion in the coastal zone the influence of marly gypsum outcrops in the upstream zone and anthropogenic sources respectively the ionic delta the ionic ratio the saturation index and stuyfzand s method were applied to evaluate geochemical processes the results obtained indicate on the one hand the phenomenon of salinization in both the coastal and the upstream zones and on the other the dilution of groundwater by recharge cation exchange is shown to modify the concentration of ions in groundwater locally with respect to salinization processes in the coastal zone the results of electrical imaging tomography show that salinity increases both with depth and laterally inland from the coastline due to seawater intrusion

geochemical evolution and timescale of seawater intrusion into the coastal aquifer of israel this study is an attempt to quantify the geochemical processes and the timescale of seawater intrusion into a coastal aquifer from changes in the major ionic composition of the water and the natural distribution of the cosmogenic isotopes 14c and 3h for that purpose we sampled saline and brackish groundwaters from the israeli coastal aquifer a multilayer sampler mls was used to obtain very high resolution 10 cm profiles across the fresh saline water interface fsi the chemical and stable isotope data revealed three distinct water types end members that are located in different zones on the route to the coastal aquifer 1 slightly modified mediterranean seawater sws 2 slightly diluted with up to 20 fresh groundwater saline groundwater sds and 3 fresh groundwater fgw the sws samples generally show an excess of total alkalinity and total dissolved inorganic carbon dic and a depletion of 13cdic and 14cdic with respect to normal seawater indicating that anaerobic oxidation of organic matter is the first diagenetic reaction that affects seawater during its penetration into the bottom sediments sds waters appear when sws is slightly diluted gain ca2 and sr2 and is depleted in k suggesting that the main processes that transform sws into sds are slight dilution with fresh groundwater and cation exchange at the fresh saline water interface sds generally shows conservative mixing with fgw inspection of chemical data from coastal aquifers around the world indicates that intensive ion exchange in slightly diluted saline groundwater is a globally important phenomenon of seawater intrusion most of our saline groundwater samples contain substantial amounts of 3h suggesting that penetration of mediterranean seawater and its inland travel to a distance of 50 100 m onshore occurred 15 30 yr ago this is supported by the 14cdic mass balance that explains the relatively low 14cdic activities in the sds as influenced by diagenesis and not by simple radioactive decay

drumlin formation in southern anglesey and arvon northwest wales this is a study of late devensian drumlins formed in southern anglesey and arvon northwest wales this area was affected by ice sheet coalescence when the welsh ice sheet met with the lrish sea ice sheet and drumlins were formed once the two had coalesced it is suggested that the drumlins were the result of net subglacial soft bed erosion and that they represent more resistant cores within the subglacial deforming layer the drumlins have either gravel or till cores and where the core was deformable large scale compressive glaciotectonic structures were seen e g dinas dinlle with local subglacial compression of 59 where the cores were more resistant e g lleiniog these were not deformed but remained as more competent masses within the deforming layer it is suggested that the less competent material flowed around the cores some remaining as a thin carapace but most of the material being removed down glacier leaving the drumlins as erosional remnants in northwest wales there is a multi till sequence that traditionally has been interpreted as having been deposited as the result of separate ice sheet advances and retreats however in this study it is suggested that the different tills were deposited as the result of ice sheet coalescence and that sites such as dinas dinlle do not show evidence of a major readvance in the retreat of the devensian ice but are indicative of continuously changing conditions within the subglacial deforming bed

anomalous moscoviense basin single oblique impact or double impact origin 1 the moscoviense basin is the most prominent mare basalt filled impact basin on the farside highlands of the moon the moscoviense basin has been studied extensively because of its characteristic geological and mineralogical context and distinct mare volcanism the success of kaguya s direct farside gravity recovery and global laser altimetry revealed that the moscoviense basin shows unique characteristics not only for geological and mineralogical but also for the geophysical contexts we measured geomorphological features of the moscoviense basin and the asymmetry suggests an oblique impact formation process moho undulation beneath the moscoviense basin however can hardly be explained by a single oblique impact formation process we propose an alternative hypothesis for the moscoviense basin formation which is called double impact scenario this scenario simultaneously accounts for the anomalously large mantle plug asymmetric surface geo morphology and excavation of olivine rich material originally located beneath the thickest crust on the moon on the basis of a set of monte carlo simulations we statistically examine the occurrence of a small spatial separation of two nearby basins the probability of double impact as seen on the moscoviense basin where the two impacts occurred 80 km apart is estimated to be about 50

hydrochemical and physical processes influencing salinization and freshening in mediterranean low lying coastal environments abstract ground and surface water chemistry and stable isotope data from the coastal zone near ravenna italy have been examined to determine the geochemical conditions and processes that occur and their implications for fresh water availability in the various brackish saline coastal environments fresh water in shallow coastal aquifers is often not enough to provide drinking water but it may sustain agriculture and natural environments such as pine forests dunes and lagoons the hydrochemistry and stable o and h isotopes of the ground and surface water near ravenna were investigated in relation to these particular environments rivers drainage channels lagoons coastal dunes paleo dunes agricultural fields and gravel pit lakes emphasis was put on the spatial distribution of ground water bodies with similar hydrochemistry most water samples are of the brackish to saline nacl type nacl concentration 300 20 000 mg l with a negative base exchange index bex that is indicative of cation exchange reactions caused by water rock interactions during the infiltration of saline water in a fresh water aquifer calcium dominated fresh water is found only in the rivers in the irrigation and drainage channels and in a few ground water samples the analysis of stable isotopes and so 4 2 cl and 18o cl ratios shows that the major chemical and physical processes determining the salinity in the area are evaporation mixing with saline water cation exchange oxidation of organic matter migration and seepage of hyper saline water the migration and upward seepage of hyper saline water driven by the hydraulic gradients induced by the drainage system causes the aquifer to become more saline over time the areas where natural recharge occurs have always been small and this in combination with the mediterranean climate results in very little natural recharge therefore unless drastic changes to the hydraulic infrastructure are made the coastal aquifer near ravenna will become more saline and will threaten the ecology of current natural areas as well as the farmland

global estimates of lunar iron and titanium contents from the chang e 1 iim data 1 until recently global high spatial resolution maps of feo and tio2 of the moon were only derived from clementine data in this study we show global maps of feo and tio2 using chang e 1 interference imaging spectrometer iim at a spatial resolution of 200 m pixel with a newly developed calibration presented here spectra obtained by iim compare well with telescopic spectra spectral parameters previously shown to be sensitive to iron and titanium derived from the calibrated iim data are highly correlated with the measured elemental concentration with r2 0 96 for feo and 0 95 for tio2 the maps were developed using this calibration histograms of basalt feo estimates have a negatively skewed distribution while tio2 distributions are unimodal they also revealed that the lunar highland crust is relatively uniform on the quadrant scale several hundred to thousand kilometers scale but inhomogenous on the global scale the area of highest elevation of the moon has very low feo and tio2 raising the question about south pole aitken spa whether its ejecta deposits covered the highest elevation and when it was formed although the average feo and tio2 abundances for basalts are highly correlated local areas of elevated iron can be associated with both high and low titanium

persistence and origin of the lunar core dynamo the lifetime of the ancient lunar core dynamo has implications for its power source and the mechanism of field generation here we report analyses of two 3 56 gy old mare basalts demonstrating that they were magnetized in a stable and surprisingly intense dynamo magnetic field of at least 13 t these data extend the known lifetime of the lunar dynamo by 160 my and indicate that the field was likely continuously active until well after the final large basin forming impact this likely excludes impact driven changes in rotation rate as the source of the dynamo at this time in lunar history rather our results require a persistent power source like precession of the lunar mantle or a compositional convection dynamo

the recharge of glacial meltwater and its influence on the geochemical evolution of groundwater in the ordovician cambrian aquifer system northern part of the baltic artesian basin abstract the geochemical evolution of groundwater in the ordovician cambrian aquifer system in the northern part of the baltic artesian basin bab illustrates how continental glaciations have influenced groundwater systems in proglacial areas the aquifer system contains water that has originated from various end members recent meteoric water glacial meltwater and relict na cl brine the saline formation water that occupied the aquifer system prior to the glacial meltwater intrusion has been diluted by meltwaters of advancing retreating ice sheets the diversity in the origin of groundwater in the aquifer system is illustrated by a wide variety in 18 o values that range from 11 to 22 5 these values are mostly depleted with respect to values found in modern precipitation in the area the chemical and isotopic composition of groundwater has been influenced by mixing between waters originating from different end members in addition the freshening of a previously saline water aquifer due to glacial meltwater intrusion has initiated various types of water rock interaction e g ion exchange carbonate mineral dissolution

identification of a holocene aquifer lagoon system using hydrogeochemical data abstract the hydrogeochemical characteristics of the cabo de gata coastal aquifer southeastern spain were studied in an attempt to explain the anomalous salinity of its groundwater this detritic aquifer is characterised by the presence of waters with highly contrasting salinities in some cases the salinity exceeds that of seawater multivariate analysis of water samples indicates two groups of water g1 and g2 group g1 is represented in the upper part of the aquifer where the proportion of seawater varies between 10 and 60 whilst g2 waters taken from the lower part of the aquifer contain 60 70 seawater in addition hydrogeochemical modelling was applied which reveals that the waters have been subject to evaporation between 25 and 35 there was a good agreement between the modelled results and the observed water chemistry this evaporation would have occurred during the holocene in a coastal lagoon environment the resulting brines would have infiltrated into the aquifer and due to their greater density sunk towards the impermeable base the characteristics of this water enabled us to reconstruct the interactions that must have occurred between the coastal aquifer and the lagoon and to identify the environmental conditions that prevailed in the study area during the middle holocene

a catalogue of impact craters larger than 200 m and surface age analysis in the chang e 5 landing area abstract chang e 5 ce 5 is the first sample return mission of china s lunar exploration and will be launched in 2020 the planned landing area is near mons rumker in oceanus procellarum it is important to have a detailed geological analysis of the landing area prior to the lunar sample collection the crater size frequency distribution curve combined with radioisotope dating of components of the returned sample by ce 5 may allow a refinement of the lunar chronology function based on a digital orthophoto map with a pixel size of 1 5 m generated from more than 700 lunar reconnaissance orbiter camera narrow angle camera images of the ce 5 landing area all impact craters larger than 200 m in diameter were extracted using the resultant crater catalogue of 32 277 craters a systematic analysis of the landing area including the crater distribution morphology characteristics and geologic model ages is conducted the results show that craters smaller than 1 000 m are denser in the east and the west parts of the region while those larger than 1 000 m tend to be more concentrated in the central part particularly within the range of 61 5 w 64 5 w within nine geologic units divided using the spectral characteristics the geologic unit of em1 eratosthenian aged mare em near the mons rumker is the youngest with a model age of 2 02 0 16 0 16 ga the three rumker plateau ir units are the oldest parts of the landing area with the largest model age of 3 49 0 12 0 073 ga the crater catalogue and the surface model age analysis results can contribute to the ce 5 mission as well as further scientific research

the relative timing of lunar magma ocean solidification and the late heavy bombardment inferred from highly degraded impact basin structures the solidification of the lunar magma ocean lmo and formation of impact basins are important events that took place on the early moon the relative timing of these events however is poorly constrained the aim of this study is to constrain the formation ages of old impact basins based on inferences of their thermal state most proposed basins formed before pre nectarian pn 5 stage do not exhibit clear concentric features in either topography or gravity suggesting substantial viscous lateral flow in the crust recent geodetic measurements reveal that the lunar crust is thinner than previously estimated indicating that an extremely high crustal temperature is required for lateral flow to occur in this study we calculate lunar thermal evolution and viscoelastic deformation of basins and investigate the thermal state at the

water quality changes in the dunes of the western belgian coastal plain due to artificial recharge of tertiary treated wastewater abstract since july 2002 tertiary treated waste water has been used to artificially recharge the phreatic aquifer of the dunes in the belgian western coastal plain the purpose of this project is to develop a sustainable water source and thereby minimize lowering of the water table while maintaining production capacity the recharged water is extracted via production wells located south and north of two ponds used for the recharge the uniqueness of this system is that the total dissolved solids in this recharge water is low 50 mg l in comparison with natural dune water 550 mg l in this paper water quality of recharge water groundwater between ponds and extraction wells extracted water and dune water is analysed the extraction water quality is determined by mixing of recharged water and dune water mineralisation of the recharge water occurs mainly by carbonate dissolution further o2 consumption no 3 reduction and oxidation of fe sulfide minerals are distinguished at the beginning of 2007 clogging of the ponds began to occur and it was observed that extraction rates and temperature of the recharge water influenced the amount of water which could be recharged using cl data it is confirmed that all the recharged water is recovered by the extraction wells finally it is concluded that the quality of the extracted water does not change significantly as a function of time

characterization of the lowland coastal aquifer of comacchio ferrara italy hydrology hydrochemistry and evolution of the system summary this study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system which controls the hydrodynamics of this coastal area forcing groundwater to flow from the bottom toward the top of the aquifer as a consequence relict seawater in stable density stratification preserved within low permeability sediments in the deepest portion of the aquifer has been drawn upward the hydrogeochemical investigations allow identifying the role of seepage and water sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry mixing between freshwater and saltwater occurs however it is neither the only nor the dominant process driving groundwater hydrochemistry in the aquifer several concurring and competing water sediment interactions as nacl solution ion exchange calcite and dolomite dissolution precipitation oxidation of organic matter and sulfate bacterial reduction are triggered by or overlap freshwater saltwater mixing the hyper salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion but suggests the presence of salt water of marine origin which was trapped in the inter basin during the holocene transgression the results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer

dielectric properties estimation of the lunar regolith at ce 3 landing site using lunar penetrating radar data abstract the second channel ch2 of the lunar penetrating radar lpr carried on the chang e 3 ce 3 yutu rover was used to determine the thickness and structure of the lunar regolith accurately revealing the true structure beneath the surface requires knowledge of the dielectric permittivity of the regolith which allows one to properly apply migration to the radar image in contrast to simple assumptions in previous studies this paper takes account of heterogeneity of the regolith and derives regolith s permittivity distribution laterally and vertically by a method widely used in data processing of terrestrial ground penetrating radar gpr we find that regolith permittivity at the landing site increases with depth more quickly than previously recognized at a depth of 2 5 3 m the dielectric constant reaches the value of solid basalt the radar image was migrated on the basis of the permittivity profile we do not find any continuous distinct layers or an apparent regolith rock interface in the migrated radargram which implies that this area is covered by relatively young poorly layered deposits

seawater intrusion and associated processes in a small coastal complex aquifer castell de ferro spain an attempt to identify the hydrogeochemical processes that accompany current or past intrusion of seawater in the castell de ferro coastal aquifer se spain was made using ionic deltas ionic ratios and saturation indices alluvial and coastal quaternary sediments and triassic marbles constitute this complex aquifer cation exchange dolomitization and calcite dissolution were identified as operating in the aquifer the cation exchange processes in the detrital materials are different from those in the marbles in addition it was determined that while the processes of marine intrusion associated with periods of low groundwater levels still persist in the detrital aquifer in the carbonate sector the flushing process characteristic of wetter conditions has begun

size frequency distribution of crater populations in equilibrium on the moon overprinting of craters by subsequent impacts and topographic degradation complicates crater statistics especially for old surfaces and small diameter crater populations a crater population is regarded as in equilibrium at a particular crater size when smaller craters are being produced at the same rate at which they are being destroyed evaluating the equilibrium state of crater populations is challenging and empirical equilibrium densities are frequently inferred by performing careful crater counts and cross comparisons on several lunar surfaces we study the size frequency distributions sfd for the crater populations which have portions in equilibrium the results are one of the few observational constraints on the sfd of crater populations in equilibrium showing that referring to empirical equilibrium densities is not safe for evaluating the equilibrium states of crater populations equilibrium densities are not positively correlated with the ages of crater populations and some populations in equilibrium have crater densities less than those previously believed to represent equilibrium conditions besides the sfd of the production population different crater removal rates at different diameters also affect the sfd of crater populations in equilibrium the equilibrium onset diameter deq of a crater population can be translated to model ages because older populations have larger deq and those for same aged surfaces are comparable we show that the crater populations studied here are in equilibrium at much smaller diameters than those predicted for same aged surfaces by crater degradation models thus indicating lower crater degradation rates on the moon and or younger ages of the counting areas

geological characterization of the chang e 4 landing area on the lunar farside abstract on january 3 2019 china s chang e 4 probe accomplishes the first ever soft landing on moon s farside in the von karman crater floor mare volcanism plain 177 59 e 45 46 s within the south pole aitken spa basin its surface in situ measurements would provide the first ground truth for lunar farside volcanism and spa materials we present a detailed geologic context topographical morphological quantitative geochemical and mineralogical characterization of a 20 20 km area centered at the chang e 4 landing site using the latest multi source high resolution orbital data sets the landing area is very flat at a baseline of 30 m with 90 of surface having slope