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

volcanism on mercury evidence from the first messenger flyby for extrusive and explosive activity and the volcanic origin of plains the first messenger flyby of mercury obtained images of 21 of the surface not seen by mariner 10 including the center and western half of the caloris basin and regions near the terminator that show details of the nature of smooth and intercrater plains these new data have helped to address and resolve a series of longstanding questions on the existence and nature of volcanism on mercury and the distribution of volcanic materials data from the mercury dual imaging system mdis on the messenger spacecraft have shown the following 1 numerous volcanic vents in the form of irregularly shaped rimless depressions are concentrated around the interior edge of the caloris basin 2 these vents appear to be sources for effusive volcanism that in one case built a shield in excess of 100 km in diameter and in some cases formed bright haloes around the vents that are interpreted to represent pyroclastic eruptions 3 lobate margins of plains units seen previously in mariner 10 data are documented in messenger images with more clarity and are often distinctive in morphology and color properties supporting the interpretation that these features are the edges of lava flow units 4 the interior of the caloris basin is filled with plains units spectrally distinctive from the rim deposits and comparison with the lunar imbrium basin and superposed impact crater stratigraphy provide evidence that these units are volcanic in origin detailed differences in the mineralogy of lava flow units so prominent in imbrium are not seen in the caloris interior 5 some of the smooth plains surrounding the exterior of the caloris basin show distinct differences in color and morphological properties supporting a volcanic origin 6 some smooth and intercrater plains units distant from the caloris basin show evidence of flooding and embayment relations unrelated to caloris ejecta emplacement local and regional geological and color relationships support a volcanic origin for these plains 7 large impact craters show a sequence of embayment of interior floor and exterior ejecta deposits that supports a volcanic origin for the embayment and filling processes 8 crater embayment and flooding relationships in selected areas suggest volcanic plains thicknesses of many hundreds of meters and local thicknesses inside impact craters of up to several kilometers 9 impact crater size frequency distributions for caloris exterior deposits including the facies of the caloris group and relatively high and low albedo smooth plains show that they are younger than plains interior to caloris and thus must be dominantly the product of post caloris volcanism these new data provide evidence that supports and confirms earlier hypotheses from mariner 10 data that volcanism was important in shaping the surface of mercury the emerging picture of the volcanic style of mercury is similar to that of the moon the other small one plate planetary body there are no major shield volcanoes e g comparable to tharsis montes on mars shallow magma reservoirs are rare and there is little evidence for surface deformation or long lived volcanic sources related to sites of upwelling mantle the close association of volcanic plains and surface deformation features suggests that future observations and analyses can help document the relation between the volcanic flux and the evolving state and magnitude of stress in the lithosphere of mercury

very recent and wide spread basaltic volcanism on mars new spacecraft data provide increasing evidence for a dynamic environment on presenta day mars exogenic processes such as impact cratering mass wasting processes and active dune migration have all been observed to modify the surface no traces of current endogenic activity have been found yet but some studies point to very localized volcanism in the last few millions of years however no systematic study of young volcanic surfaces had been performed so far we present absolute model age determinations of plains volcanism on mars as derived from impact crater sizefrequency distributions extended areas in tharsis the largest volcanoa tectonic region on mars have been resurfaced by lava flows in the last few tens of millions of years we also present results on the rheologic properties of these lava flows inferred from morphometric measurements yield strengths are in the range of 100a 300 pa and viscosities reach values of 10 2 to 10 3 pa s indicating basaltic compositions the results imply that mars retained until recently and probably still retains enough internal heat to produce widea spread plaina style volcanism producing lowa viscosity lava flows throughout large parts of tharsis

eruption history of the elysium volcanic province mars abstract volcanism has played a significant role in shaping the surface of mars volatiles released during eruptions profoundly altered the composition and density of the martian atmosphere in the past quantifying the amounts of volcanic outgassing has been attempted regionally and globally however volume estimates of erupted volcanic material in time are still poorly constrained here we show the first eruption frequency record of a volcanic region the elysium volcanic province which is the second largest volcanic province on mars studied lava flows show model ages ranging from 3 4 ga to 60 ma together with observed resurfacing ages the visible record of volcanic activity extends back to 3 9 ga based on our 190 model ages continuous volcanic activity is apparent with a major peak at 2 2 ga in the last 1 gyr the activity rapidly waned although the majority of volcanic material including volatiles released to the atmosphere erupted within a short time span of less than 200 ma activity continued until the very recent past extrapolating the eruption record it appears likely that this region of mars is still volcanically active today our derivation of the eruption record has profound implications for global thermal and atmospheric modeling indicating sustained heat production melt generation and magma ascent at a single location over most of the planet s geological history

cone penetration testing cpt in antarctic firn an introduction to interpretation commercial cone penetration testing cpt equipment was adapted to allow penetrative testing in hard polar firn to depths of 10 m the apparatus is hydraulically driven rate controllable and able to penetrate firn with a resistance of 10 mpa it can be mounted on many types of typical polar vehicles requiring connection to only hydraulics and 12 v electricity data recorded include both cone tip resistance and sleeve friction a parameter not previously examined through such testing this paper describes the development and calibration of the equipment and examines factors including snow density penetration rate and cone size and shape that are shown to affect cpt interpretation cpt can be used efficiently in polar environments to potentially provide estimates of physical parameters in hard firn to substantial depth

a brief introduction to cone penetration testing cpt in frozen geomaterials the cone penetration test has been successfully used to classify soil for 100 years however it has received only limited contemporary use in frozen geomaterials the historical and contemporary use of the cone penetration test in various frozen geomaterials is considered here and contemporary data from recent work in polar snow are examined it is probable that many material physical properties e g density strength and microstructure can be obtained directly from cone penetration testing it appears under utilized as a contemporary scientific and engineering investigative tool in frozen geomaterials

the age of lunar mare basalts south of the aristarchus plateau and effects of secondary craters formed by the aristarchus event abstract using crater size frequency distributions csfds and careful discrimination of primary and secondary impact craters in the mare region south of aristarchus crater we reexamined the age of unit p60 determined previously by hiesinger et al 2003 to be one of the youngest basaltic surfaces on the moon owing to the apparently young age of these basalts this region is a potential site for future sample return missions we investigated this 55 000 km2 region with lunar reconnaissance orbiter camera lroc images to assess potential variations in csfds across the unit particularly in light of heavy contamination by secondary craters from aristarchus crater and to determine the age s of p60 over its full areal extent we are able to match within one standard error the previously determined age using approximately the same counting area in addition we defined twelve regions between the rays of secondaries to determine if and how the ages of p60 might vary across the unit for these inter ray regions we find a systematic progression of ages from west to east ranging from youngest 1 ga in the west to 1 8 ga southwest of aristarchus to 2 2 ga south of aristarchus and finally to 2 7 ga southeast of aristarchus this variation in ages is not solely attributable to secondary cratering indicating it must be at least partially due to volcanic resurfacing the northwestern most extension of p60 may belong to a different unit owing to topographic and crater distribution differences analysis of the summed csfd for p60 provides evidence for emplacement of the younger basalts

on the relative and absolute ages of seven lunar front face basins ii from the crater counts abstract from counts of postbasin craters larger than 30 km in diameter lying within or near to seven giant front face lunar basins relative ages for the basins may be obtained these relative ages correlate well with absolute basin ages found from viscosity arguments in r b baldwin 1987 icarus 70 from crater counts the basins are in the following sequence of increasing relative age orientale imbrium crisium serenitatis nectaris humorum and the unnamed basin lying between werner and the altai ring the absolute ages from baldwin 1987 range from 3 80 to 4 30 109 years while a correlation with the relative ages of this paper yields a range of 3 79 to 4 27 109 years the discrepancy is largely due to serenitatis where the debris from imbrium has presumably buried some post serenitatis craters from both sets of data there is no evidence that a terminal lunar cataclysm ever occured

magma source transition of lunar mare volcanism at 2 3 ga mare basalts provide insights into the composition and thermal history of the lunar mantle the ages of mare basalts suggest a first peak of magma activity at 3 2 3 8 ga and a second peak at 2 ga in this study we reassess the correlation between the titanium contents and the eruption ages of mare basalt units using the compositional and chronological data updated by selene kaguya using morphological and geological criteria we calculated the titanium content of 261 mare units across a representative area of each mare unit in the procellarum kreep terrane where the latest eruptions are located an increase in the mean titanium content is observed during the eratosthenian period as reported by previous studies we found that the increase in the mean titanium content occurred within a relatively short period near approximately 2 3 ga suggesting that the magma source of the mare basalts changed at this particular age moreover the high titanium basaltic eruptions are correlated with a second peak in volcanic activity near 2 ga the high titanium basaltic eruptions occurring during the last volcanic activity period can be explained by the three possible scenarios 1 the ilmenite bearing cumulate rich layer in the core mantle boundary formed after the mantle overturn 2 the basaltic material layers beneath the lunar crust formed through upwelling magmas and 3 ilmenite bearing cumulate blocks remained in the upper mantle after the mantle overturn

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

volumes of lunar lava ponds in south pole aitken and orientale basins implications for eruption conditions transport mechanisms and magma source regions in an effort to characterize individual eruptive phases and events 86 isolated mare deposits ponds in the lunar south pole aitken and orientale regions were analyzed to obtain information on areas volumes and other characteristics deposits likely to represent single eruptive episodes have area mean values of 2000 km2 in the south pole aitken basin and 1100 km2 in the orientale basin pond volumes range from 35 to 8745 km3 with a mean value of 860 km3 for south pole aitken and 10 to 1280 km3 with a mean value of 240 km3 for the orientale region no evidence was found for shallow crustal magma reservoirs the relatively common occurrence of sinuous rilles in orientale is consistent with very high effusion rates and the large volumes of individual eruptive episodes tens to many hundreds of km3 are comparable to flood basalt eruption volumes on earth pond morphologies are consistent with extrusion from deep probably subcrustal reservoirs distribution of deposits suggests that many ponds may be derived from single reservoirs comparison of ponds in both basins shows a higher areal density and average volume of lava ponds in the south pole aitken basin relative to the orientale area this is plausibly attributed to the extreme depths of the south pole aitken basin and the correspondingly thinner crust there relative to the orientale region these observations are consistent with magma ascent and eruption mechanisms that are strongly dependent on the overpressurization of deep seated source regions the subsequent propagation of dikes and the thickness of the intervening lunar crust through which these dikes must rise

mineralogy of young lunar mare basalts assessment of temporal and spatial heterogeneity using m3 data from chandrayaan 1 abstract a comparative assessment of the mineralogy of young basalts 1 2 ga to 2 8 ga from the western nearside moscoviense basin and the orientale basin of the moon has been made using level 2 moon mineralogy mapper m3 data from the chandrayaan 1 mission spectral data characteristics of the individual units have been generated from fresh small craters to minimize the complications due to space weathering representative spectra for individual units and the derived spectral parameters band centers and integrated band depth ratio have been used to study composition of these young basalts a modified approach of gaffey et al gaffey m j cloutis e a kelley m s reed k l 2002 mineralogy of asteroids in asteroids iii the university of arizona press tucson pp 183 204 for olivine pyroxene mixtures and the methodology of adams adams j b 1974 j geophys res 79 4829 4836 http dx doi org 10 1029 jb079i032p04829 for interpreting pyroxene type have been used to improve our understanding of the spectral behavior of these basalts most of the young basalts of oceanus procellarum are characterized by abundant olivines and they show complex volcanic history vast exposures of olivine concentrated units having higher abundance of olivine content than high ca pyroxenes are emplaced in the northern oceanus procellarum region mostly they show distinct stratigraphic gradation with the immediately underlying units of relatively lower olivine content the moscoviense unit shows signatures of fe rich glasses along with clinopyroxenes the basalts of orientale basin are typically devoid of olivine and are rich in high ca pyroxene thus mineralogy of these mare basalts which erupted during the late stage volcanism vary across the moon s surface however broader observations reveal apparently higher feo content in the younger basalts of western nearside and orientale region

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

the constitution and structure of the lunar interior the current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period missions of the 1960s including the rangers surveyors and lunar orbiters as well as earth based telescopic studies laid the groundwork for the apollo program and provided a basic understanding of the surface its stratigraphy and chronology through a combination of remote sensing surface exploration and sample return the apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean in particular the discovery of anorthite clasts in the returned samples led to the view that a large portion of the moon was initially molten and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle and plagioclase flotation cumulates that make up the crust smith et al 1970 wood et al 1970 this model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the moon the intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the moon s interior much of this new knowledge is a direct result of data acquired from the successful clementine and lunar prospector missions as well as the analysis of new lunar meteorites as will be seen results from these studies have led to many fundamental amendments to the magma ocean model much of what we know from sample analyses has been previously summarized elsewhere and only their most important aspects will be discussed in this chapter the reader is referred to the relevant chapters in the books basaltic volcanism on the terrestrial planets basaltic volcanism study project 1981 the

the 3 d geological model around chang e 3 landing site based on lunar penetrating radar channel 1 data high frequency lunar penetrating radar lpr data from an instrument on the lunar rover yutu from the chang e 3 ce 3 robotic lander were used to build a three dimensional 3 d geological model of the lunar subsurface structure the ce 3 landing site is in the northern mare imbrium more than five significant reflection horizons are evident in the lpr profile which we interpret as different period lava flow sequences deposited on the lunar surface the most probable directions of these flows were inferred from layer depths thicknesses and other geological information moreover the apparent imbrian paleoregolith homogeneity in the profile supports the suggestion of a quiescent period of lunar surface evolution similar subsurface structures are found at the nasa apollo landing sites indicating that the cause and time of formation of the imaged phenomena may be similar between the two distant regions

an igneous origin for features of a candidate crater lake system in western memnonia mars the association of channels inner terraces and delta like features with martian impact craters has previously been interpreted as evidence in favor of the past existence of crater lakes on mars however examination of a candidate crater lake system in western memnonia suggests instead that its features may have formed through igneous processes involving the flow and ponding of lava accumulations of material in craters and other topographic lows throughout much of the study region have characteristics consistent with those of volcanic deposits and terraces found along the inner flanks of some of these craters are interpreted as having formed through drainage or subsidence of volcanic materials channels previously identified as inlets and outlets of the crater lake system are interpreted instead as volcanic rilles these results challenge previous interpretations of terrace and channel features in the study region and suggest that candidate crater lakes located elsewhere should be reexamined

quantification of the hand hardness test snow hardness is the resistance to penetration it can be measured by the swiss rammsonde or estimated by the hand hardness test according to the international classification of seasonal snow on the ground icssg snow hardness is divided into five levels without ice however the hand test is subjective and provides only an index value of snow hardness the main objective of this study was to determine the hardness using an alternative method which can be applied in the same way as the hand test and which can deliver accurate data in this study the conventional hand hardness test was used additionally a digital force gauge push pull gauge was applied where the hardness was measured horizontally for comparison with the hand hardness test the push pull gauge could be provided with five different attachments the size and design of each attachment corresponded to the equivalent application of the hand hardness test fist four fingers one finger pencil knife this paper indicates how snow hardness measured by hand is related to snow hardness measured with the push pull gauge moreover the variability of the hardness both vertical and horizontal is demonstrated the results show agreement with the icssg for hand hardness indices 3 4 and 5 for hand hardness indices 1 and 2 the range indicated by the icssg is below the lower quartile of the measurements

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

a new technique for estimating the thickness of mare basalts in imbrium basin 1 the total volume of extrusive volcanism on the moon provides a basic thermal and geologic constraint and accurate volume assessments are contingent upon constraining lava flow depths here employing uv vis data from the clementine mission we estimate mare thickness values in the imbrium basin by analyzing ejecta from large 10 km diameter impact craters that penetrate or failed to penetrate through the mare mare thickness values are found to range from at least 2 km at the basin center to 1 5 2 0 km in the buried ring shelf annulus this corresponds to a basalt volume of 1 3 106 km3 almost a factor of two greater than the volume estimated from partially filled craters alone our results indicate that thickness measurements from penetrating craters combined with minimum estimates from partially filled and non penetrating craters provide a more complete picture of the spatial variation of basalt thickness values than could previously be obtained

ages and stratigraphy of lunar mare basalts in mare frigoris and other nearside maria based on crater size frequency distribution measurements 1 we report on ages derived from impact crater counts for exposed mare basalt units in the northern part of the lunar nearside hemisphere mare frigoris the eastern and northeastern part of the nearside hemisphere lacus temporis joliot hubble goddard mare marginis and mare smythii the central part of the nearside hemisphere palus putredinis mare vaporum and sinus medii and the southwestern part of the nearside hemisphere grimaldi cruger rocca a lacus aestatis and schickard in mare frigoris we dated 37 basalt units showing ages from 2 61 to 3 77 gyr with most units being formed in the late imbrian period between 3 4 and 3 8 gyr ago in mare vaporum we dated six spectrally homogeneous units that show model ages of 3 10 to 3 61 gyr our model ages of basalts in mare marginis range from 3 38 to 3 88 gyr and are mostly older than basalts in mare smythii 3 14 3 48 gyr the model ages of four units in sinus medii indicate that the basalts in this region formed 3 63 to 3 79 gyr ago we find an excellent agreement of our crater size frequency model ages of the palus putredinis area which contains the apollo 15 landing site with the radiometric ages of apollo 15 samples according to our crater counts basalts in palus putredinis are 3 34 gyr old and this compares favorably with the radiometric ages of 3 30 3 35 gyr of the olivine normative and quartz normative basalts of the apollo 15 landing site lacus aestatis is a small irregular shaped mare patch in the southwestern nearside and shows an imbrian age of 3 50 gyr basalts in lacus temporis in the northeastern nearside formed between 3 62 and 3 74 gyr ago and are therefore older than the basalts in lacus aestatis we found that basalts in craters of the southwestern nearside schickard grimaldi cruger and rocca a are also mostly younger than basalts in craters of the northeastern nearside hubble joliot and goddard while basalt ages vary between 3 16 and 3 75 gyr in the southwest basalts in the northeast are 3 60 3 79 gyr old these results confirm and extend the general distribution of ages of mare basalt volcanism and further underline the predominance of older mare basalt ages in the eastern and southern nearside and in patches of mare peripheral to the larger maria in contrast to the younger basalt ages on the western nearside oceanus procellarum

lunar mare basalt flow units thicknesses determined from crater size frequency distributions accurate lava flow unit thicknesses estimates are necessary to place constraints on volcanic flux estimates we refine the technique of using the shape of crater size frequency distribution csfd curves to estimate the thickness of individual lunar mare flow units we find that a characteristic knee often observed in csfd curves is reasonably interpreted to represent the presence of two lava flow units separated in time and that the diameter at which this knee occurs is related to the thickness of the overlying flow unit examination of 58 curves with this characteristic knee in several lunar nearside basins oceanus procellarum imbrium tranquillitatis humorum cognitum nubium and insularum allowed us to identify flow units that have not been detected in low sun images we found that the range of flow unit thickness is 20 220 m and the average is 30 60 m this technique expands considerably the ability to assess lava flow unit thicknesses and volumes on the moon and planets

origin of discrepancies between crater size frequency distributions of coeval lunar geologic units via target property contrasts abstract recent work on dating copernican aged craters using lunar reconnaissance orbiter lro camera data re encountered a curious discrepancy in crater size frequency distribution csfd measurements that was observed but not understood during the apollo era for example at tycho copernicus and aristarchus craters csfds of impact melt deposits give significantly younger relative and absolute model ages amas than impact ejecta blankets although these two units formed during one impact event and would ideally yield coeval ages at the resolution of the csfd technique we investigated the effects of contrasting target properties on csfds and their resultant relative and absolute model ages for coeval lunar impact melt and ejecta units we counted craters with diameters through the transition from strength to gravity scaling on two large impact melt deposits at tycho and king craters and we used pi group scaling calculations to model the effects of differing target properties on final crater diameters for five different theoretical lunar targets the new csfd for the large king crater melt pond bridges the gap between the discrepant csfds within a single geologic unit thus the observed trends in the impact melt csfds support the occurrence of target property effects rather than self secondary and or field secondary contamination the csfds generated from the pi group scaling calculations show that targets with higher density and effective strength yield smaller crater diameters than weaker targets such that the relative ages of the former are lower relative to the latter consequently coeval impact melt and ejecta units will have discrepant apparent ages target property differences also affect the resulting slope of the csfd with stronger targets exhibiting shallower slopes so that the final crater diameters may differ more greatly at smaller diameters besides their application to age dating the csfds may provide additional information about the characteristics of the target for example the transition diameter from strength to gravity scaling could provide a tool for investigating the relative strengths of different geologic units the magnitude of the offset between the impact melt and ejecta isochrons may also provide information about the relative target properties and or exposure degradation ages of the two units robotic or human sampling of coeval units on the moon could provide a direct test of the importance and magnitude of target property effects on csfds

mare volcanism in the lunar farside moscoviense region implication for lateral variation in magma production of the moon 1 accurate estimates of the duration and volume of extrusive volcanism of the moon are essential for understanding the lunar thermal evolution here using new high resolution images obtained by the selene terrain camera we determined the thicknesses and ages of basalts in mare moscoviense one of the most prominent mare deposits on the farside mare volcanism in mare moscoviense was active for at least 1 5 ga following the formation of the moscoviense basin mare basalts are estimated to be at least 600 m thick corresponding to a total volume of 9 500 16 000 km 3 the long duration and large volume of extrusive volcanism are plausibly attributed to the thinner crust of the moscoviense basin relative to those of other farside basins from a comparison with mare volume within a same sized nearside basin we concluded that a magma production in the farside mantle was 3 10 times less than that of the nearside

confident thickness estimates for planetary surface deposits from concealed crater populations abstract an improved technique is presented to determine more accurately deposit thicknesses of any surface units using crater size frequency distributions csfds this new approach enables thickness estimates of deposits that completely cover their underlying unit i e where no flooded craters are observed here the crater populations of the unit of interest and its underlying unit or a representative surface area are measured and their cratering model ages determined the csfd of the younger unit is then treated as if it had the same age as the older unit and the expected cumulative numbers of craters for each bin size are calculated the crater deficiency for each bin size is then determined by subtracting the expected cumulative crater number from the observed cumulative crater number per bin the probability is calculated such that the crater deficiency corresponds to the age of the older underlying unit the crater bin size where we are 95 confident that these craters are there but just covered by the younger unit is chosen to derive the deposit thickness value using known crater diameter rim height relationships we demonstrate the use of the method at two sites of different scales and settings on mars pickering crater and lunae planum and compare our estimates with those obtained by other methods for the lunae planum area a significantly higher minimum thickness of 840 m is predicted

the thickness and volume of young basalts within mare imbrium basaltic volcanism is one of the most important geologic processes of the moon research on the thickness and volume of late stage basalts of mare imbrium helps better understand the source of lunar volcanism and eruption styles based on whether apparent flow fronts exist or not the late stage basalts within mare imbrium were divided into two groups namely upper eratosthenian basalts uem and lower eratosthenian basalts lem employing the topographic profile analysis method for uem and the crater excavation technique for lem we studied the thickness and distribution of eratosthenian basalts in mare imbrium for the uem units their thicknesses were estimated to be similar to 16 34 2 m with several layers of individual lava similar to 8 13m inside the estimated thickness of lem units was similar to 14 45 1 m with a trend of reducing thickness from north to south the measured thickness of late stage basalts around the chang e 3 landing site similar to 371m was quite close to the results acquired by the lunar penetrating radar carried on board the yutu rover similar to 35m the total volume of the late stage basalts in mare imbrium was calculated to be similar to 8 671 320 km 3 which is 4 times lower than that of schaber s estimation similar to 4x10 4 km 3 our results indicate that the actual volume is much lower than previous estimates of the final stage of the late basaltic eruption of mare imbrium together the area flux and transport distance of the lava flows gradually decreased with time these results suggest that late stage volcanic evolution of the moon might be revised plain language summary the late stage younger than 3 1ga volcanism of the moon deposited large areas of basalts in mare imbrium and oceanus procellarum these basalts have different colors dark and blue compared to old basalts sampled by apollo and luna missions in order to understand how these young basalts erupted in mare imbrium we estimated their thickness and volume using multiple data using detailed visible and near infrared spectral data in combination with topographic information we estimated the height of lava flows and the thickness of late stage rocks excavated by impact craters our results indicate that these young basalts have a thickness of tens of meters and a total volume of similar to 8 671 320 km 3 both values are smaller than those of previous estimates suggesting a smaller volcanic activity than previously thought these results indicate that the magmatic activity gradually weakened in this region

mare volcanism reinterpretation based on kaguya lunar radar sounder data the lunar radar sounder lrs onboard kaguya selene detected widespread horizontal reflectors under some nearside maria previous studies estimated that the depths of the subsurface reflectors were up to several hundreds of meters and suggested that the reflectors were interfaces between mare basalt units the comparison between the reflectors detected in the lrs data and surface age maps indicating the formation age of each basalt unit allows us to discuss the lower limit volume of each basalt unit and its space and time variation we estimated volumes of basalt units in the ages of 2 7 ga to 3 8 ga in the nearside maria including mare crisium mare humorum mare imbrium mare nectaris mare serenitatis mare smythii and oceanus procellarum the lower limit volumes of the geologic units estimated in this study were on the order of 103 to 104 km3 this volume range is consistent with the total amount of erupted lava flows derived from numerical simulations of thermal erosion models of lunar sinuous rille formation and is also comparable to the average flow volumes of continental flood basalt units formed after the paleozoic and calculated flow volumes of archean komatiite flows on the earth the lower limits of average eruption rates estimated from the unit volumes were on the order of 10 5 to 10 3 km3 yr the estimated volumes of the geologic mare units and average eruption rate showed clear positive correlations with their ages within the same mare basin while they vary among different maria compared within the same age range

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dating very young planetary surfaces from crater statistics a review of issues and challenges determining the ages of young planetary surfaces relies on using populations of small often sub km diameter impact craters due to the higher frequency at which they form smaller craters however can be less reliable for estimating ages as their size frequency distribution is more susceptible to alteration with debate as to whether they should be used at all with the current plethora of meter scale resolution images acquired of the lunar and martian surfaces small craters have been widely used to derive model ages to establish the temporal relation of recent geologic events in this review paper we discuss the many factors that make smaller craters particularly challenging to use and should be taken into consideration when crater counts are confined to small crater diameters establishing confidence in a model age ultimately requires an understanding of the geologic context of the surface being dated as reliability can vary considerably and limitations of the dating technique should be considered in applying ages to any geologic interpretation

precipitation of iron in microbial mats of the spring waters of borra caves vishakapatnam india some geomicrobiological aspects the borra caves vishakapatnam india can be described as a speleothem cave with significant amounts of unexplored microbial mats in spring waters here we present the first observations and hypotheses on the possible impact of the microorganisms in these mats on the cave formation focusing on their role on iron mineral precipitation the spring waters ph neutral 7 5 7 7 contained dissolved metals like iron and the organic mat sludge ph 7 0 7 3 had a toc content of approximately 5 4 wt geochemically the spring waters deep below the microbial mats contained fe 369 ppb sr 198 ppb and the organic mat sludge contained mg 9 ppm fe 427 ppb zn 149 ppb sr 190 ppb xrd observations displayed fe minerals dominantly hematite minor amounts of zinc gallium sulfide and nitrofuryl compounds at least four groups of bacteria identified by direct microscopy and sem edx on the basis of morphology could be observed in all samples leptothrix like organisms entombed bacterial mineral sheaths a few stalks of gallionella like organisms and some additional bacteria that could not be further identified leptothrix like organisms contained 43 22 60 08 wt fe and the mineral precipitated near and around these bacteria in the actual unaltered samples on site contained 30 76 45 22 wt fe as identified and quantified by sem edx this study indicates that the precipitation of these iron rich mats in the spring waters could be linked to the presence of abundant active communities of iron precipitating bacteria at borra caves vishakapatanam

microbiology and geochemistry in a hydrogen sulphide rich karst environment abstract cueva de villa luz a hypogenic cave in tabasco mexico offers a remarkable opportunity to observe chemotrophic microbial interactions within a karst environment the cave water and atmosphere are both rich in hydrogen sulphide measured h 2 s levels in the cave atmosphere reach 210 ppm and so 2 commonly exceeds 35 ppm these gases plus oxygen from the cave air are absorbed by freshwater that accumulates on cave walls from infiltration and condensation oxidation of sulphur and hydrogen sulphide forms concentrated sulphuric acid drip waters contain mean ph values of 1 4 with minimum values as low as 0 1 the cave is fed by at least 26 groundwater inlets with a combined flow of 200 300 l s inlet waters fall into two categories those with high h 2 s content 300 500 mg l mean p co 2 0 03 0 1 atm and no measurable o 2 and those with less than 0 1 mg l h 2 s mean p co 2 0 02 atm and modest o 2 content up to 4 3 mg l both water types have a similar source as shown by their dissolved solid content however the oxygenated water has been exposed to aerated conditions upstream from the inlets so that original h 2 s has been largely lost due to outgassing and oxidation to sulphate increasing the sulphate concentration by about 4 chemical modelling of the water shows that it can be produced by the dissolution of common sulphate carbonate and chloride minerals redox reactions in the cave appear to be microbially mediated sequence analysis of small subunit 16 s ribosomal rna genes of 19 bacterial clones from microbial colonies associated with water drips revealed that 18 were most similar to three thiobacilli spp a genus that often obtains its energy from the oxidation of sulphur compounds the other clone was most similar to acidimicrobium ferrooxidans a moderately thermophilic mineral sulphide oxidizing bacterium oxidation of hydrogen sulphide to sulphuric acid and hence the cave enlargement is probably enhanced by these bacteria two cave enlarging processes were identified 1 sulphuric acid derived from oxidation of the hydrogen sulphide converts subaerial limestone surfaces to gypsum the gypsum falls into the cave stream and is dissolved 2 strongly acidic droplets form on the gypsum and on microbial filaments dissolving limestone where they drip onto the cave floors the source of the h 2 s in the spring waters has not been positively identified the villahermosa petroleum basin within 50 km to the northwest or the el chichon volcano 50 km to the west may serve as source areas for the rising water depletion of 34 s values 11 7 for sulphur stabilized from h 2 s in the cave atmosphere along with the hydrochemistry of the spring waters favour a basinal source

formation of fe silicates and fe oxides on bacterial surfaces in samples collected near hydrothermal vents on the southern explorer ridge in the northeast pacific ocean samples collected in low temperature 2 50 degrees c waters near hydrothermal vents of the southern explorer ridge in the northeast pacific ocean contained fine 500 nm fe and mn oxide and fe silicate particles coating bacterial surfaces partially to totally mineralized bacteria along with bacterial exopolymers were covered with a mixture of poorly ordered si rich fe oxides possibly ferrihydrite mn oxides and fe silicates possibly nontronite minerals occur as very fine 2 20 nm granular material fine 20 100 nm needles and sheets small 200 500 nm nodules and filaments i e mineralized exopolymers under saturation conditions we infer that bacterial surfaces provided nucleation sites for poorly ordered oxides and silicates the formation of fe and mn oxides was likely initiated by the direct binding of soluble fe and mn species to reactive sites like carboxyl phosphate and hydroxyl groups present within the bacterial cell wall and the exopolymers fe silicate formation involved a more complex binding mechanism whereas metal ions such as fe possibly bridged reactive sites within the cell walls to silicate anions to initiate silicate nucleation

bioconstructions in ochreous speleothems from lava tubes on terceira island azores abstract the ochreous speleothems examined here were obtained from a lava tube on terceira island azores and show compact mineralized areas intermixed with zones in which bacterial structures are evident bacterial layers of filament like structures are common throughout the deposits but differences in microstructure among the different speleothems were observed reflecting a broad morphological range of deposits the structures and minerals detected in the speleothems betray their biogenic origin gallionella and leptothrix were the two most frequently observed morphotypes and probably the main contributors to speleothem formation however dgge analysis indicated the presence of another bacterial population with a predominance of proteobacteria that could also contribute to iron hydroxide oxide precipitation the sheaths of leptothrix cells and stalks of gallionella cells were associated with large amounts of extrapolymeric substances eps which play a role in biomineralization processes independently of the taxa present mineral deposits were composed of poorly ordered si rich ferrihydrite a typical mineral phase of biogenic fe precipitates in this microscopy study of interrelationships between mineral precipitates and associated microorganisms and their structures we attribute bacteria to have an important role in constructing these speleothems through their metabolic activity these bacteria cause the precipitation of ferrihydrite but their mineral structures could also act as nucleation points for passive mineral precipitation finally the build up of bacterial mineral structures and later cementation processes seems responsible for the formation of mineral layers that confer consistency to the speleothem our findings point to bacterial activity as the main factor determining speleothem structure and formation

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

the case for a younger imbrium basin new 40ar 39ar ages of apollo 14 rocks petrographically and chemically well characterized rocks of the apollo 14 landing site 12 impact melt breccias 3 clast free impact melt rocks 2 granulitic rocks 1 cataclastic noritic anorthosite 1 shocked gabbronorite 1 mare basalt and 1 plagioclase single crystal have been dated by the 40ar 39ar technique the samples represent two different formations at the apollo 14 site 1 small lithic clasts 10 specimens from fragmental breccia 14063 ejected from the 26 ma old cone crater and one clast mare basalt from cone crater soil 14140 and 2 large rock samples 10 specimens collected throughout the regolith of the landing site the first group of samples has exposure ages close to 26 ma and 40ar 39ar ages ranging from 3 86 to 4 09 ga which indicates that breccia 14063 was assembled 3 86 ga ago the second group of samples displays lower 40ar 39ar ages ranging from 3 73 to 3 85 ga we interpret breccia 14063 as part of a nectarian megabreccia unit which was incorporated into the fra mauro formation as a megablock by secondary mass wasting of the ejecta blanket of a local pre imbrian crater the remaining samples are thought to represent clasts of the apollo 14 subregolith basement megabreccia defined as the fra mauro formation consequently the reported ages of these clasts confirm previous suggestions that the fra mauro formation and therefore the imbrium basin is only 3 75 ga old and not 3 85 ga as commonly assumed

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

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

first evidence of pleistocene ochre production from bacteriogenic iron oxides a case study of the upper palaeolithic site at the san teodoro cave sicily italy abstract the use of iron pigments is well documented in the archaeological horizons of the different parts of the world since the middle pleistocene the mineralogical and chemical composition of the pigments allowed defining in most cases their inorganic origin which were then used after a limited transformation and manipulation the use of a biogenic ochraceous pigment and its manipulation has recently been described in a late holocene archaeological horizon of the american continent here we describe the earliest case of archaeological use of ferrous pigment produced by iron oxidising bacteria feob the first identified in a european epigravettian late upper palaeolithic layer at the san teodoro site in sicily italy samples of the ochraceous archaeological deposit overlying a large burial site were analysed according to current methods of physical analysis and sem highlighting a matrix of bacterial structures and a chemical composition coherent with biogenic productions the physical chemical analysis of the archaeological material from the palaeolithic site and of the modern bacteriogenic iron sediments from two close springs gave consistent results even after heat treatment in absence of terra rossa or other easily available inorganic ferrous materials in the hinterland of their site the hunter gatherers identified several possible water sources rich of pigment used for covering a multiple burial the implications of these results influence interpretations of the ecology of the late glacial and epigravettian sites in europe especially in relation to problems such as the increasing complexity of behaviours the need to establish rituals and the search for materials

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

beginning and end of lunar mare volcanism mare volcanism on the moon is commonly attributed to an important but relatively short lived epoch of internal heating after 3 900 myr bp but before about 2 500 myr bp refs 1 2 although some studies suggested that mare volcanism had started earlier3 5 than times indicated by dated lunar samples only recently have photogeological spectral and geochemical data6 8 documented the importance of a pre 4 000 myr bp epoch similarly early earth based geological mapping revealed a bright rayed crater lichtenberg superposed by mare units9 thereby indicating that mare volcanism must have extended to times significantly more recent than 3 100 myr bp lunar orbital photography confirmed this inferred strati graphical relationship10 but crater statistics indicated that the youngest units were at least twice the age of copernicus or between 1 700 and 2 000 myr bp refs 11 13 we present here the inferred distribution and style of the early phases of mare volcanism based on current evidence and conclude that certain regions of the moon underwent two distinct pulses of igneous activity we then examine crater statistics for the post lichtenberg mare unit and other selected units and conclude that mare volcanism extended to a time comparable with that of the copernicus impact or 1 myr bp these reassessments of the oldest and youngest maria provide new constraints on geophysical models of the internal thermal history of the moon

long lived volcanism on the lunar farside revealed by selene terrain camera we determined model ages of mare deposits on the farside of the moon on the basis of the crater frequency distributions in 10 meter resolution images obtained by the terrain camera on selene selenological and engineering explorer kaguya most mare volcanism that formed mare deposits on the lunar farside ceased at 3 0 billion years ago suggesting that mare volcanism on the moon was markedly reduced globally during this period however several mare deposits at various locations on the lunar farside also show a much younger age clustering at 2 5 billion years ago these young ages indicate that mare volcanism on the lunar farside lasted longer than was previously considered and may have occurred episodically

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

detectability of subsurface interfaces in lunar maria by the lrs selene sounding radar influence of mineralogical composition 1 the lunar radar sounder lrs of the selene mission has detected horizontal subsurface features at depths of a few hundreds of meters within all major lunar maria we have mapped these features at global scale and found a heterogeneous geographical distribution which correlates negatively with the maps of tio 2 and feo obtained from uv vis measurements by the clementine probe high concentration of ilmenite fetio 3 in the basaltic mare lava can explain this correlation this mineral being a strong absorber for low frequency electromagnetic waves thus absence of detection of subsurface interfaces by lrs on a large portion of lunar maria does not necessarily imply that these interfaces are actually absent

the compositional and physical properties of localized lunar pyroclastic deposits abstract lunar localized pyroclastic deposits are low albedo deposits with areas 2 these deposits were difficult to study before the turn of the millennium because of the lack of available high spatial resolution data with the launch of the lunar reconnaissance orbiter kaguya and chaandrayan 1 new sets of diverse high spatial resolution data are now available using several of these data sets we conducted a study of 34 localized pyroclastic deposits globally for each localized pyroclastic deposit we examined topography to estimate pyroclastic volume and juvenile proportions s band radar backscatter thermal infrared derived measures of surficial rock abundance and regolith density and mineral abundances our goals are to 1 quantitatively characterize the physical and mineralogical properties of each localized pyroclastic deposit 2 investigate the physical and mineralogical variations among localized pyroclastic deposits 3 compare these properties of localized 2 to regional pyroclastic deposits 2500 km 2 and 4 provide useful parameters for future volcanological modeling from this study we find that 1 localized pyroclastic deposits exhibit low relief structures 2 the surface rock abundance and circular polarization ratio of localized pyroclastic deposits display a wide range of values 0 2 0 5 and 0 3 0 6 respectively 3 the glass abundance of localized pyroclastic deposits vary between 0 and 80 wt 4 there are four types of localized pyroclastic deposits based upon the surface rock abundance and glass abundance parameters 5 pyroclastic deposits within the same floor fractured crater tend to have similar properties and 6 localized pyroclastic deposits are diverse with respect to regional pyroclastic deposits but a subset of localized pyroclastic deposits have similar physical and mineralogical properties to regional pyroclastic deposits

numerical modeling of lava regolith heat transfer on the moon and implications for the preservation of implanted volatiles 1 we have performed a series of numerical simulations of heat transfer between lunar lava flows and the underlying regolith with the goal of determining the depths in the substrate beneath which implanted extralunar volatiles would survive outgassing by the downward propagating heat pulse exogenous materials of interest include solar wind and solar flare particles and the cosmogenic products of galactic cosmic ray gcr particles emplaced in the lunar regolith early in solar system history extraction and analysis during future lunar missions would yield information about the evolution of the sun and inner solar system environment particles implanted in regolith deposits may be protected from gardening and saturation if buried by a lava flow but must be sufficiently deep in the regolith to survive the consequent heating our simulations include detailed treatments of lava and regolith thermophysical properties thermal conductivity specific heat capacity which vary widely over the temperature range relevant to lava flows in the lunar environment 200 to 1500 k simulations adopting temperature dependent properties together with a treatment of latent heat of lava crystallization indicate that implanted volatiles would be fully preserved at depths greater than 20 cm beneath 1 m thick lava flows 60 deeper than predicted by simulations employing constant properties these results highlight the necessity of appropriate prescription of material properties consideration of the range of lunar lava flow thicknesses allows us to determine the range of depths from which pristine samples may be recovered

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

cone penetration testing in snow the application of the electric cone penetrometer test in snow has been investigated and compared with results from the ram penetrometer test which is normally used for snow profiling and slope stability analysis a special cone penetrometer system was built consisting of a sensitive 1 cm2 electric cone depth transducer and battery operated chart recorder the instruments were tested in april 1985 at three different locations in the swiss alps and the test results were compared with those of the ram penetrometer tests the tests yielded repeatable results up to a depth of 4 m with a high resolution of different snow layers the electric cone tests show more layers than found in the ram profile and snow pit analyses in soft snow the ram resistances appear to be on average about 30 lower than cone resistance values recommendations are given for the future use of electric cone penetration testing in snow key words snow snowpack analysis cone penetration test ram penetrometer cone resistance ram

small scale lunar farside volcanism abstract we identified and mapped 28 mare basalt occurrences between the australe and south pole aitken basins on the southern lunar farside and determined their absolute model ages amas by performing crater size frequency distribution csfd measurements our study area can be subdivided into seven major mare basalt occurrences in and around bolyai roche v rosseland pauli and roche craters south of both rosseland and coblentz craters as well as mare patches between eotvos and roche craters the amas of the mare basalts in and around bolyai crater range from 2 1 ga to 3 5 ga two units varying drastically within short distances the mare patches south of coblentz crater contain nine units that have amas ranging from 2 1 ga to 3 8 ga the mare basalts in roche v crater show an ama of 2 2 ga we mapped seven volcanic units in rosseland crater and derived amas for five of these units the mare basalts in rosseland crater show the youngest amas found in our study area ranging from 1 5 ga to 2 9 ga the mare basalt occurrence south of rosseland crater shows significantly older ages with an ama of 3 3 ga the mare basalts in pauli and roche craters show amas from 1 7 ga to 3 1 ga the mare patches between eotvos and roche craters show a similar range of amas from 1 9 ga to 3 1 ga the amas of the mare basalts in our study show that the lunar farside was volcanically active for nearly as long as the lunar nearside 1 2 ga ago or at least longer than previously thought 2 5 ga ago and predicted by models of the ascent and eruption of lunar basalts in addition we calculated thicknesses and volumes of the investigated mare basalts with thicknesses between 21 m and 172 m and volumes from 0 1 km3 to 379 km3 the mare basalts in our study area show a wide range of dimensions similar to other mare basalts of the lunar near and farsides

investigation of newly discovered lobate scarps implications for the tectonic and thermal evolution of the moon abstract using observations of lunar scarps in apollo panoramic camera photos binder and gunga 1985 tested competing models for the initial thermal state of the moon i e whether it was initially completely molten or if the molten portion was limited to a global magma ocean binder and gunga 1985 favored the concept of an initially molten moon that had entered into a late stage epoch of global tectonism since the start of the lunar reconnaissance orbiter mission thousands of new small lobate scarps have been identified across the lunar surface with high resolution images from the lunar reconnaissance orbiter camera lroc as such we selected spatially random scarps and reevaluated the fault dynamical calculations presented by binder and gunga 1985 additionally we examined the geometry and properties of these fault scarps and place better constraints on the amount of scarp related crustal shortening we found that these low angle thrust faults 23 have an average relief of 40 m and average depths of 951 m using crater size frequency distribution csfd measurements we derived absolute model ages for the scarp surfaces proximal to the trace of the fault and found that the last slip event occurred in the last 132 ma along with young model ages lunar lobate scarps exhibit a youthful appearance with their crisp morphologies which is indicative of late stage horizontal shortening in conclusion interior secular cooling and tidal stresses cause global contraction of the moon

volcanism in the solar system the myriad bodies that occur in the solar system show a wide range of physical properties exploration by spacecraft during the past four decades has shown that volcanism a major mechanism by which internal heat is transported to the surface is common on many of these bodies

thicknesses of lava flows in satellite images comparison of layered mare units with terrestrial analogs abstract recent advances in satellite imaging technology have greatly improved our observations of planetary surfaces the lunar reconnaissance orbiter lro narrow angle camera nac records images with resolutions on average of 0 5 m per pixel resolving meter scale features on the surface of the moon nac images have revealed layered deposits interpreted to be sequences of mare basalt flows in the walls of impact craters on the lunar nearside however caution must be exercised in the interpretation of surface processes from morphologies of features that are close to the limits of detectability our goal is to quantify where that limit is for lava flow stratigraphy here we report on a terrestrial analog study conduced to better constrain limitations in the measurements of thicknesses of lava flows observed in high resolution satellite collected images using worldview 2 satellite images we mapped layered basalt flows at three sites in the wai anae and ko olau ranges of o ahu hawai i fieldwork conducted at these sites allowed for assessment of the accuracy of image interpretations we found that flow thickness estimates made using worldview 2 images overestimated thicknesses of individual lava flows measured in the field at all eight locations visited by a factor of 1 2 to 3 5 a primary reason for this overestimation by remote sensing analysis is that many outcropping layers within a transect contain more than one individual flow a distinction that is not visible in satellite images however the mean thickness of the layers seen in the orbital data was 0 8 to 1 7 times the outcrop thickness measured in the field suggesting that the remote measurements should be considered estimates of the outcrop thickness rather than the thickness of individual lava flows measurements of layered lunar mare lava units in lro nac images provided layer thicknesses that ranged from

thermal and magmatic evolution of the moon as with all science our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data this process invigorates the intellectual foundation on which old models are tested and new concepts are built just as the application of new observational tools to lunar science in 1610 galileo s telescope and 1840 photography yielded breakthroughs concerning the true nature of the lunar surface the computational and technological advances highlighted by the apollo and post apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the moon 1 1 pre apollo view of the thermal and magmatic evolution of the moon many of the early views of the moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the sun and the moon prophetically myths involving the lunar deities mwuetsi from zimbabwe and coyolxauhqui from mexico told of rather violent or catastrophic events in which the moon was expunged from the earth numerous ancient scientific observations were made about the nature of the moon ranging from those uncovered in early neolithic sites that correctly identified mare crisium and mare humorum to the insights made by greek philosophers such as anaxagoras ca 500 428 b c and democritus ca 460 370 b c who attached terrestrial analogues to its character stone mountains with the advent of the telescope 1610 and photography 1840 as scientific tools for lunar exploration semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation initially modern terrestrial geological analogs were extended to the moon lunar highlands volcanic craters seas combined with the rigors of computational modeling these observational data were extended to predict the original thermal state of the moon and its thermal and magmatic history its proximity to the earth

crater based dating of geological units on mars methods and application for the new global geological map abstract the new post viking generation of mars orbital imaging and topographical data provide significant higher resolution details of surface morphologies which induced a new effort to photo geologically map the surface of mars at 1 20 000 000 scale although from unit superposition relations a relative stratigraphical framework can be compiled it was the ambition of this mapping project to provide absolute unit age constraints through crater statistics in this study the crater counting method is described in detail starting with the selection of image data type locations both from the mapper s and crater counter s perspectives and the identification of impact craters we describe the criteria used to validate and analyse measured crater populations and to derive and interpret crater model ages we provide examples of how geological information about the unit s resurfacing history can be retrieved from crater size frequency distributions three cases illustrate short intermediate and long term resurfacing histories in addition we introduce an interpretation independent visualisation of the crater resurfacing history that uses the reduction of the crater population in a given size range relative to the expected population given the observed crater density at larger sizes from a set of potential type locations 48 areas from 22 globally mapped units were deemed suitable for crater counting because resurfacing ages were derived from crater statistics these secondary ages were used to define the unit age rather than the base age using the methods described herein we modelled ages that are consistent with the interpreted stratigraphy our derived model ages allow age assignments to be included in unit names we discuss the limitations of using the crater dating technique for global scale geological mapping finally we present recommendations for the documentation and presentation of crater statistics in publications

the spatial variability of snow resistance on potential avalanche slopes since snow avalanches are believed to release from zones of localized weakness knowledge of snow strength patterns is important for determining slope stability and for applying effective avalanche control measures in this study the spatial variability of snow resistance an index of snow strength and depth were measured and compared with terrain features on two inclined slopes a refined instrument allowed the strength of an entire snow slab to be characterized in a short time the spatial pattern of trees appeared to affect the pattern of snow depth at one site where a significant linear relationship was found between snow depth and average snow resistance these results suggest that localized snow depth variations may be important in snow strength genesis although a linear relationship existed at that site additional factors may be critically relevant a second site with more complex terrain features and less localized wind drifting did not show a linear relationship between depth and average resistance instead complex patterns of resistance demonstrated that many factors contribute to snow resistance in particular the snow overlying rocks was found to have significantly weaker resistance than that in adjacent areas not over rocks

composition and structure of nanocrystalline fe and mn oxide cave deposits implications for trace element mobility in karst systems abstract fe and mn oxides are ubiquitous highly reactive minerals in the environment which often control the distribution and speciation of trace elements in soils and aquatic systems pautler cave in southwest illinois contains fe and mn oxide deposits with properties that differ spatially and temporally two depositional environments exist in the cave fe and mn precipitation where anoxic groundwater enters the oxic cave passage seep deposition and direct deposition from the cave stream seep waters have higher concentrations of ca2 fe2 and mn2 lower ph and lower o2 aq concentrations relative to stream waters in addition seep waters have nearly constant 18o values that are similar to the yearly average of local precipitation whereas cave stream waters have more erratic 18o values and appear to be influenced by seasonal variations of 18o in rainfall these differences suggest that the seep water source has a longer residence time in the subsurface than the cave stream water fe oxides are solely found as seep deposits whereas mn oxides are deposited both by groundwater seepage and cave streams freshly precipitated fe oxides are composed of ferrihydrite and filamentous material consistent with biomineralization structures of the microbial genera gallionella and leptothrix mn oxide minerals consist of 7 and 10 a phyllomanganates having a range of three dimensional order mn oxide samples show a greater heavy metal and trace element content compared to fe oxides and mn oxides deposited by cave streams have higher concentrations of metals than mn oxide seep deposits in addition phyllomanganate particle morphologies and crystallinity display a compositional dependence with platelet size and phyllomanganate sheet stacking order decreasing with increasing ba and trace element content and decreasing ca content these properties also appear to correlate with dissolved mn ii in the source water these observations suggest that fe and mn oxide minerals in oxic cave systems affect trace element concentrations in carbonate fed springs and illustrate a previously unrecognized limitation on the transport of inorganic nutrients and contaminants in karst aquifers

preservation potential of implanted solar wind volatiles in lunar paleoregolith deposits buried by lava flows abstract the lunar surface is bathed in a variety of impacting particles originating from the solar wind solar flares and galactic cosmic rays these particles can become embedded in the regolith and or produce a range of other molecules as they pass through the target material the moon therefore contains a record of the variability of the solar and galactic particle fluxes through time to obtain useful temporal snapshots of these processes discrete regolith units must be shielded from continued bombardment that would rewrite the record over time one mechanism for achieving this preservation is the burial of a regolith deposit by a later lava flow the archival value of such deposits sandwiched between lava layers is enhanced by the fact that both the under and over lying lava can be dated by radiometric techniques thereby precisely defining the age of the regolith layer and the geologic record contained therein the implanted volatile species would be vulnerable to outgassing by the heat of the over lying flow at temperatures exceeding 300 700 c however the insulating properties of the finely particulate regolith would restrict significant heating to shallow depths we have therefore modeled the heat transfer between lunar mare basalt lavas and the regolith in order to establish the range of depths below which implanted volatiles would be preserved we find that the full suite of solar wind volatiles consisting predominantly of h and he would survive at depths of 13 290 cm for 1 10 m thick lava flows respectively a substantial amount of co co2 n2 and xe would be preserved at depths as shallow as 3 7 cm beneath meter thick flows given typical regolith accumulation rates during mare volcanism the optimal localities for collecting viable solar wind samples would involve stacks of thin mare lava flows emplaced a few tens to a few hundred ma apart in order for sufficient regolith to develop between burial events obtaining useful archives of solar system processes would therefore require extraction of regolith deposits buried at quite shallow depths beneath radiometrically dated mare lava flows these results provide a basis for possible lunar exploration activities

is the linne impact crater morphology influenced by the rheological layering on the moon s surface insights from numerical modeling linne is a simple crater with a diameter of 2 23 km and a depth of 0 52 km located in northwestern mare serenitatis recent high resolution data acquired by the lunar reconnaissance orbiter camera revealed that the shape of this impact structure is best described by an inverted truncated cone we perform morphometric measurements including slope and profile curvature on the digital terrain model of linne finding the possible presence of three subtle topographic steps at the elevation of 20 100 and 200 m relative to the target surface the kink at 100 m might be related to the interface between two different rheological layers using the isale shock physics code we numerically model the formation of linne crater to derive hints on the possible impact conditions and target physical properties in the initial setup we adopt a basaltic projectile impacting the moon with a speed of 18 km s 1 for the local surface we consider either one or two layers in order to test the influence of material properties or composite rheologies on the final crater morphology the one layer model shows that the largest variations in the crater shape take place when either the cohesion or the friction coefficient is varied in particular a cohesion of 10 kpa marks the threshold between conical and parabolic shaped craters the two layer model shows that the interface between the two layers would be exposed at the observed depth of 100 m when an intermediate value 200 m for the upper fractured layer is set we have also found that the truncated cone morphology of linne might originate from an incomplete collapse of the crater wall as the breccia lens remains clustered along the crater walls while the high albedo deposit on the crater floor can be interpreted as a very shallow lens of fallout breccia the modeling analysis allows us to derive important clues on the impactor size under the assumption of a vertical impact and collision velocity equal to the mean value and on the approximate large scale preimpact target properties observations suggest that these large scale material properties likely include some important smaller scale variations disclosed as subtle morphological steps in the crater walls furthermore the modeling results allow advancing some hypotheses on the geological evolution of the mare serenitatis region where linne crater is located unit s14 we suggest that unit s14 has a thickness of at least a few hundreds of meters up to about 400 m

formation age of the lunar crater giordano bruno using the terrain camera onboard the japanese lunar explorer selene kaguya we obtained new high resolution images of the 22 kilometer diameter lunar crater giordano bruno based on crater size frequency measurements of small craters 200 m in diameter superposed on its continuous ejecta the formation age of giordano bruno is estimated to be 1 to 10 ma this is constructive evidence against the craters medieval age formation hypothesis

the geologic evolution of mars episodicity of resurfacing events and ages from cratering analysis of image data and correlation with radiometric ages of martian meteorites we have investigated 12 prominent regions on mars in detail with respect to their geologic evolution through time on the basis of detailed geologic mapping exercises and determining age relationships through crater counting techniques using imagery new data in combination with previously obtained data have been analyzed by way of a refined method of cratering age extraction that also gives fine details of periods of resurfacing we have found that there has been volcanic and fluvial glacial geologic activity on the martian surface at all times from 4 ga ago until today this activity shows episodic pulses in intensity of both volcanic and fluvial glacial processes at 3 8 3 3 ga 2 0 1 8 ga 1 6 to 1 2 ga 800 to 300 m y 200 m y and 100 m y and a possible weaker phase around 2 5 2 2 ga ago in between these episodes there was relative quiescence of volcanic and or fluvial glacial activity the episodes we find on the martian surface in the crater frequency analyses of hrsc moc and themis data coincide with some age groups of the martian meteorites 1 3 ga 600 300 m y 170 m y it appears that the surface activity expressions and their episodicity are related to the interior evolution of the planet when convection in the asymptotic stationary state changes from the so called stagnant lid regime to an episodic behavior similarities in episodic behavior are found for the other terrestrial planets venus the earth s moon and the earth itself suggesting a common general relationship in the evolutionary tracks

an assemblage of lava flow features on mercury 1 in contrast to other terrestrial planets mercury does not possess a great variety of volcanic features its history of volcanism instead largely manifest by expansive smooth plains however a set of landforms at high northern latitudes on mercury resembles surface flow features documented on earth the moon mars and venus the most striking of such landforms are broad channels that host streamlined islands and that cut through the surrounding intercrater plains together with narrower more sinuous channels coalesced depressions evidence for local flooding of intercrater plains by lavas and a first order analysis of lava flow rates the broad channels define an assemblage of flow features formed by the overland flow of and erosion by voluminous high temperature low viscosity lavas this interpretation is consistent with compositional data suggesting that substantial portions of mercury s crust are composed of magnesian iron poor lithologies moreover the proximity of this partially flooded assemblage to extensive volcanic plains raises the possibility that the formation of these flow features may preface total inundation of an area by lavas emplaced in a flood mode and that they escaped complete burial only due to a waning magmatic supply finally that these broad channels on mercury are volcanic in nature yet resemble outflow channels on mars which are commonly attributed to catastrophic water floods implies that aqueous activity is not a prerequisite for the formation of such distinctive landforms on any planetary body

young mare volcanism in the orientale region contemporary with the procellarum kreep terrane pkt volcanism peak period 2 billion years ago 1 the crater retention ages of the mare deposits within the orientale multi ring impact basin are investigated using 10 m resolution images obtained by the selene kaguya spacecraft in order to constrain the volcanic history of the moon around the nearside farside boundary precise crater counting analyses reveal that mare deposits in the orientale region are much younger than previously estimated 2 9 ga mare basalt in the eastern part of mare orientale and 1 8 2 2 ga mare deposits in lacus veris and lacus autumni maria along the northeastern rings of the basin the latter age estimates indicate that the orientale region experienced volcanic activities 2 billion years after the basin formation impact the dominance of a uniform surface age across the mare deposits in the peripheral regions strongly suggests that these volcanic eruptions are contemporary with the elevated volcanic activity episode proposed for the procellarum kreep terrane on the lunar nearside at 2 ga and that this activity peak is much more widespread than previously estimated the longevity of mare volcanism in the orientale region further suggests high initial temperatures and or high content of heat producing elements in the underlying mantle of this region

timing and characteristics of the latest mare eruption on the moon unraveling the timing and duration of mare volcanism on the moon is essential for understanding its thermal evolution the end of mare volcanism is poorly constrained because mare basalts are incompletely sampled in this study employing selene kaguya high resolution images we performed new crater size frequency measurements for 49 young mare units 3 0 ga in the procellarum kreep terrane pkt in which the latest magma eruption of the moon occurred mare volcanism in this region continued until 1 5 ga suggesting that volcanic activity in this region ceased 1 0 ga after the magma eruption had globally ceased 2 5 3 0 ga volcanic activity may have peaked 1 8 2 2 ga ago the youngest basalts occur around the aristarchus plateau and the kepler crater which are located in the central region of the pkt it is likely that heating in the crust due to the concentration of heat producing elements in the pkt delayed cooling of a partial melting zone in the underlying mantle in contrast with previous basalt dating in this region our results indicate a higher correlation between ages and spectral types of mare basalts the young mare units in the pkt tend to have spectral types corresponding to high titanium contents while low titanium basalts occur mainly in the early stage the titanium variation in mare basalts may reflect vertical heterogeneity in tio2 content in the upper mantle beneath the pkt

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

estimation of the permittivity and porosity of the lunar uppermost basalt layer based on observations of impact craters by selene 1 we have investigated the geological conditions below two lava flow units through determining the bulk permittivity and porosity in the uppermost basalt layer to depths of a few hundred meters we use a newly developed method based on three data sets obtained by the lunar radar sounder lrs multiband imager mi and terrain camera tc onboard the selenological and engineering explorer selene kaguya spacecraft the bulk permittivity of the uppermost basalt layer is calculated as the ratio of the apparent radar depth to the thickness of the uppermost basalt layer its thickness can be constrained from the excavation depths of two types of craters haloed and nonhaloed craters these craters are identified on the basis of feo and or tio2 maps created from the mi data these excavation depths are determined based on the measurement of the crater diameter using the tc data the apparent radar depth is derived from the time delay between the surface echo and subsurface echo measured by lrs near the craters the bulk permittivities are estimated to be 2 8 5 5 in a lava flow unit of mare humorum and 4 2 18 0 in a lava flow unit of mare serenitatis these bulk permittivities are indicative of porous basalt layers with the porosities of 19 51 in the unit of humorum and 0 33 in the unit of serenitatis the estimated porosities would be mainly explained by two different sources intrinsic voids of lava and impact induced cracks

lunar farside volcanism in and around the south pole aitken basin abstract we identified and mapped 129 mare basalt deposits in and around the south pole aitken spa basin and determined absolute model ages amas for 101 of these units by performing crater size frequency distribution csfd measurements the derived amas range from 2 2 ga to 3 7 ga with the youngest deposits within antoniadi crater and the oldest deposits at jules verne crater our investigations indicate a major peak in volcanic activity between 3 6 ga and 3 2 ga which is a similar time range as the major volcanic activity on the nearside and the rest of the farside however a second peak in volcanic activity 2 2 2 5 ga as observed for the nearside and parts of the farside is not observed for the mare deposits within the spa basin combining all amas derived for farside mare basalts reveals that volcanic activity was more abundant and lasted longer on the nearside than on the farside we propose that the stripping of insulating crust by the large spa forming impact event in combination with lower amounts of heat producing elements like th might be responsible for the reduced volcanic activity in the spa basin in addition we estimated the thicknesses and volumes of the investigated mare deposits with thicknesses between 31 m and 273 m and volumes of 1 km to 2630 km the mare basalt deposits in and around the spa basin show a wide range of dimensions similar to other mare basalts of the near and farsides a trend between the amas and the estimated volumes was not observed but the mare deposits within the large northern craters e g apollo ingenii or leibnitz seem to be generally larger and more voluminous than the mare basalt deposits at the center of the spa basin

possible lunar lava tube skylight observed by selene cameras 1 we discovered a vertical hole on the moon which is a possible lava tube skylight using data from selene s two high resolution cameras the terrain camera and the multi band imager the hole is nearly circular 65 m in diameter and located in a sinuous rille at the marius hills region a volcanic province on the lunar nearside we observed the hole at various solar illumination conditions and estimated its depth to be 80 to 88 m the depth diameter ratio is much larger than for typical impact craters there are neither conspicuous deposits indicating volcanic eruptions from the hole nor are there pit craters adjacent to the hole that could be related to an underlying fault or dike the area around the hole is covered by a thin 20 to 25 m lava sheet which may help protect the lava tube from collapse due to meteorite bombardment

experimental analysis of snow micropenetrometer smp cone penetration in homogeneous snow layers the cone penetration test cpt is widely used to determine in situ soil and snow characteristics and stratigraphy for avalanche forecasting knowledge about snow stratigraphy is of crucial import

mineralogical variation of the late stage mare basalts the last major phases of lunar volcanism occurred mainly in oceanus procellarum and mare imbrium and produced spectrally unique medium and high titanium basalts the composition and distribution of these basalts provide a record of the late stage thermal evolution of the moon to study the spectral and mineralogical variations of the late stage mare basalts 31 distinct units were mapped employing a range of remote sensing data their inferred mineralogical characteristics were studied by analyzing the spectral features of small fresh craters derived from the moon mineralogy mapper m3 data the strongest olivine spectral signatures were found around lichtenberg crater while the units with the lowest olivine pyroxene ratio occurred mainly in the southern kepler crater and some local areas in oceanus procellarum the olivine pyroxene ratio decreases progressively from the lichtenberg crater to the southern units the northern and southern units within mare imbrium have higher olivine pyroxene ratios than the central ones the inferred abundance of olivine appears to vary stratigraphically with the younger flows being more olivine rich however the stratigraphically younger units around euler crater in mare imbrium which present as dark red hues in the integrated band depth image of m3 were found to have lower olivine pyroxene ratios than the units around lichtenberg crater shown as light red hues in oceanus procellarum it could be interpreted that the late stage mare basalts around lichtenberg crater originated from a more olivine rich source than those around euler crater

characteristics of lunar mare deposits in smythii and marginis basins implications for magma transport mechanisms an analysis of 34 lunar lava flows and ponds in the eastern limb smythii and marginis basins was undertaken to examine and model the first stages of secondary crustal formation and assess processes involved in magma transport and eruption in order to isolate the characteristics of single eruptive episodes we focused on discrete mare ponds adjacent to the major mafia mean values for areas and volumes of deposits estimated to be good candidates for single eruptive phases are large approximately 950 1000 km 2 and 200 km 3 respectively these eruptive volumes are commensurate with the largest known terrestrial eruptions flood basalts the lack of geomorphological structures indicative of shallow magma reservoirs indicates that deep probably subcrustal source regions are prevalent with respect to crustal thickness relationships the magnitude and frequency of eruptive events are observed to be greatest in areas of thinnest crust specifically regions of major maria mare smythii mare marginis occur in areas of thinnest crust while isolated ponds occur where the crust is relatively thicker this is consistent with the correlation observed globally between crustal thickness and the magnitude and frequency of eruptive events ages of volcanic flows and pyroclastic events range from early imbrian to imbfian eratosthenian but are concentrated most heavily between 3 80 3 60 ga suggesting a period of peak volcanism beginning around 3 85 ga and lasting approximately 200 ma however the existence of dark halo crater clusters in non mare units within the region suggests the presence of cryptomaha which would indicate an earlier onset of volcanism and a volume of mare matehal potentially greater than that currently exposed on the surface typical nearest neighbor distances suggest deposits derive from reservoirs 100 km in diameter the observations made here are consistent with a magma transport model in which plumes rising diapirically stall at a density boundary under the lunar crust and propagate dikes to the surface through overpressufization

geology and scientific significance of the rumker region in northern oceanus procellarum china s chang e 5 landing region the rumker region 41 45 n 49 69 w is located in northern oceanus procellarum of the moon mons rumker is the most distinctive geological feature in the area the region is characterized by prolonged lunar volcanism late imbrian period to eratosthenian period forming multiple geologic units in the area including very low ti to low ti mare basalts high ti mare basalts and volcanic complexes each geologic unit has distinct element composition and mineral assemblages the rumker region overlying the procellarum kreep terrain was selected as the landing region for china s chang e 5 lunar sample return mission prelanding analyses of the geologic context and scientific potential are reported in this contribution we conducted detailed geological mapping using image spectral and altimetry data fourteen geological units were defined a geologic map was constructed and the geologic history was outlined the western mare units im1 im2 and im3 are imbrian aged 3 4 3 5 ga representing the major stage of lunar mare eruptive volcanism the eastern young mare units em3 and em4 2 ga are among the youngest mare basalts on the moon they have never been explored in situ or studied in the laboratory we suggest that samples returned from the eastern mare unit em4 could answer many fundamental questions and that this unit should be listed as the top priority landing site for chang e 5 sample return mission

mini rf and lroc observations of mare crater layering relationships abstract the lunar maria cover approximately 17 of the moon s surface discerning discrete subsurface layers in the mare provides some constraints on thickness and volume estimates of mare volcanism multiple types of data and measurement techniques allow probing the subsurface and provide insights into these layers including detailed examination of impact craters mare pits and sinuous rilles and radar sounders unfortunately radar sounding includes many uncertainties about the material properties of the lunar surface that may influence estimates of layer depth and thickness because they distribute material from depth onto the surface detailed examination of impact ejecta blankets provides a reliable way to examine deeper material using orbital instruments such as cameras spectrometers or imaging radars here we utilize miniature radio frequency mini rf data to investigate the scattering characteristics of ejecta blankets of young lunar craters we use circular polarization ratio cpr information from twenty two young fresh lunar craters to examine how the scattering behavior changes as a function of radius from the crater rim observations across a range of crater size and relative ages exhibit significant diversity within mare regions five of the examined craters exhibit profiles with no shelf of constant cpr near the crater rim comparing these cpr profiles with lroc imagery shows that the magnitude of the cpr may be an indication of crater degradation state this may manifest differently at radar compared to optical wavelengths comparisons of radar and optical data also suggest relationships between subsurface stratigraphy and structure in the mare and the block size of the material found within the ejecta blanket of the examined craters twelve have shelves of approximately constant cpr as well as discrete layers outcropping in the subsurface and nine fall along a trend line when comparing shelf width with thickness of subsurface layers these observations suggest that surface cpr measurements may be used to identify near surface layering here we use ejected material to probe the subsurface allowing observations of near surface stratigraphy that may be otherwise hidden by layers higher from remote observations