concretionary methane seep carbonates and associated microbial communities in black sea sediments abstract gas seeps in the euxinic northwestern black sea provide an excellent opportunity to study anaerobic methane based ecosystems with minimum interference from oxygen dependent processes an integrated approach using fluorescence and electron microscopy fluorescence in situ hybridization lipid biomarkers stable isotopes 13c and petrography revealed insight into the anatomy of concretionary methane derived carbonates currently forming within the sediment around seeps some of the carbonate concretions have been found to be surrounded by microbial mats the mats harbour colonies of sulphate reducing bacteria dss group and archaea anme 1 putative players in the anaerobic oxidation of methane isotopically depleted lipid biomarkers indicate an uptake of methane carbon into the biomass of the mat biota microbial metabolism sustains the precipitation of concretionary carbonates significantly depleted in 13c the concretions consist of rectangularly orientated rod to dumbbell shaped crystal aggregates made of fibrous high mg calcite the sulphate reducing bacteria exhibit intracellular storage inclusions and magnetosomes with greigite fe3s4 indicating that iron cycling is involved in the metabolism of the microbial population transfer of fe3 into the cells is apparently mediated by abundant extracellular vesicles resembling known bacterial siderophore vesicles marinobactine in size 20 to 100 nm and structure

the role of magma buoyancy on the eruption of lunar basalts it has long been recognized that mare basalts on the moon are preferentially located both on the earth facing hemisphere and within large impact basins a popular model that accounts for this observation assumes that these magmas were denser than the lunar crust that they accumulated at the crust mantle interface and that eruptions occurred only when this magma chamber became overpressurized in this paper we re evaluate this model and argue that it is not consistent with the available data nor with models of dike propagation as an alternative hypothesis we propose that magma buoyancy is the predominant factor that determines whether mare basalts erupt at the surface or form crustal intrusions instead we have computed the densities of mare basaltic magmas and find that some are in fact less dense than the moon s upper anorthositic crust based on the widely accepted view that the lunar crust becomes more mafic with depth we also show that all mare basaltic magmas should be less dense than the lower portion of the crust thus if the upper anorthositic crust was regionally removed by an impact event then any mare basaltic magma could have risen to the surface there based on buoyancy considerations alone in support of this model we note that mare basalts are indeed found wherever geophysical crustal thickness models predict the upper crust to be absent furthermore many of the basalts that erupted within the anorthositic highlands are predicted to be less dense than the underlying crust based on remote sensing data the high titanium flows within oceanus procellarum are somewhat problematical to our model in that an anorthositic crust is predicted to be present beneath them using results from recent lunar thermal models we suggest that these magmas may have overcome their negative buoyancy in the crust by possessing superliquidus temperatures if magma buoyancy does indeed control whether or not a basaltic eruption will occur then this implies that the quantity of magma produced beneath the south pole aitken basin was about 10 times less than that of the nearside fl 2001 elsevier science b v all rights reserved

fluid migration and origin of a mud volcano in the northern apennines italy the role of deeply rooted normal faults introductionsurface seeps of gas oil and salinewaters areconsideredtobeindicatorsof deep seated hydrocarbon accumu lationandhavebeenused forover60years as a guide to hydrocarbonprospectivity a wide spectrum ofseepages belongs to di erent geologi cal settings e g camerlenghi etal 1992 1995 thrasher etal 1996 schulz etal 1997 kopf etal 1998 graue 2000 spectacular seepagescan be found in basins with highsedimentation rates that generateoverpressureandmuddiapirism gu liev and feyzullayev 1996 up dipcarrier beds and active tectonic fea tures act as channels for subsurface uidandlocalizesurfaceemissionsuptotens orevenahundred kilometresfrom the reservoir thrasher etal 1996 during migration the domi nant mechanism that changeshydrocarbon composition is phasepartitioning migration of hydrocar bons is then largely the result ofbuoyancy of the free phase formedduringthisprocess matthews 1996 eventually thegeologyofthebasinisthe key to interpreting complicated uidmigrationpathways manystud ies simply focus on the oil and gascomponents of the migrating uidrather than on the characteristics ofthewaterandmudthatareassociatedwithhydrocarbonmigrationandalsoextruded by spontaneous seeps eventhough water is invoked as beingresponsibleforatleastlighthydrocar bon removal klusman and saaed 1996 watersofdi erentprovenancecontributetotheascending uidsandtheir geochemical characteristics canhelp in understanding their evolutionduring diagenesis and migration e g white 1965 hanor 1987 holyshandto th 1996 thispaperpresentssomeanalytical data from a spontaneoussurface seep bearing saline water mud gas and oil at the foothills ofthe northern apennines the aimsare i to provide some insight intothedepthandoriginofthe uidsandthe nature of the seepage pathway and ii tode nethelossofsubsurface uids accumulation related to thegeologicalpattern geological setting and structuralcontrol of the regnano mudvolcanoin the external portion of the nor thern apennines spontaneous uidemissions are distributed along twobelts borgia etal 1986 nanni andvivalda 1999 minissaleetal 2000 the rst belt stretches along the poplainfoothills whilethesecondoneisinternal and runs nearly parallel tothe main apenninic divide fig 1 theregnanomudvolcanoconsistsofmud breccias and mud ows spread ing over an area of 0 5km

integrated 3d geophysical and geological modelling of the hercynian suture zone in the champtoceaux area south brittany france this paper combines geological knowledge and geophysical imagery at the crustal scale to model the 3d geometry of a segment of the hercynian suture zone of western europe in the champtoceaux area brittany france the champtoceaux complex consists of a stack of metamorphic nappes of gneisses and micaschists with eclogite bearing units the exhumation of the complex during early carboniferous times was accompanied by deformation during regional dextral strike slip associated with a major hercynian shear zone the south armorican shear zone sasz dextral shearing produced a km scale antiformal structure with a steeply dipping axial plane and a steeply eastward plunging axis armor 2 deep seismic profile shows that the regional structure was cut by a set of faults with northward thrusting components based on the seismic constraint direct 2d crustal scale modelling was performed throughout the champtoceaux fold on seven radial gravity profiles also using geological data and density measurements from field and drill hole samples the 3d integration of the cross sections the digitised geological map and the structural information foliation dips insure the geometrical and topological consistency of all sources of data the 2d information is interpolated to the whole 3d space using a geostatistical analysis finally the 3d gravity contribution of the resulting model is computed taking into account densities for each modelled geological body and compared to the bouguer anomaly the final 3d model is thus compatible with the seismic and gravity data as well as with geological data main geological results derived from the modelling are i the overall 3d geometry of the south dipping thrust system interpreted on the seismic profile emphasises northward thrusting and folding of the champtoceaux complex which was coeval with strike slip along the south armorican shear zone ii the gravity modelling suggests the presence of a relatively dense body below the champtoceaux complex that could be interpreted as a result of relative uplift of midcrustal material during thrusting along the e w trending wrench thrust system iii the northern limb of the champtoceaux anticline is a relatively shallow feature and iv vigneux synkinematic granitic body is a laccolith sheared and rooted along the southern branch of the sasz and spreads away from the strike slip zone within weak country rocks d 2004 elsevier b v all rights reserved

insights into mare basalt thicknesses on the moon from intrusive magmatism abstract magmatic intrusions preferentially spread along interfaces marked by rigidity and density contrasts thus the contact between a lunar mare and its substratum provides a preferential location for subsequent magmatic intrusions shallow intrusions that bend the overlying layer develop characteristic shapes that depend on their radius and on the overlying layer flexural wavelength and hence on their emplacement depth we characterize the topography of seven previously identified candidate intrusive domes located within different lunar maria using data from the lunar orbiter laser altimeter their topographic profiles compare very well with theoretical shapes from a model of magma flow below an elastic layer supporting their interpretation as intrusive features this comparison allows us to constrain their intrusion depths and hence the minimum mare thickness at these sites these new estimates are in the range 400 1900 m and are generally comparable to or thicker than previous estimates when available the largest thickness 1700 m is obtained next to the hortensius and kepler areas that are proposed to be the relicts of ancient volcanic shields

a combined spectrophotometric and morphometric study of the lunar mare dome fields near cauchy arago hortensius and milichius in this study we examine the spectral and morphometric properties of the four important lunar mare dome fields near cauchy arago hortensius and milichius we utilize clementine uv vis mulfispectral data to examine the soil composition of the mare domes while employing telescopic ccd imagery to compute digital elevation maps in order to determine their morphometric properties especially flank slope height and edifice volume after reviewing previous attempts to determine topographic data for lunar domes we propose an image based 3d reconstruction approach which is based on a combination of photoclinometry and shape from shading accordingly we devise a classification scheme for lunar marc domes which is based on a principal component analysis of the determined spectral and morphometric features for the effusive mare domes of the examined fields we establish four classes two of which are further divided into two subclasses respectively where each class represents distinct combinations of spectral and morphometric dome properties as a general trend shallow and steep domes formed out of low tio2 basalts are observed in the hortensius and milichius dome fields while the domes near cauchy and arago that consist of high tio2 basalts are all very shallow the intrusive domes of our data set cover a wide continuous range of spectral and morphometric quantities generally characterized by larger diameters and shallower flank slopes than effusive domes a comparison to effusive and intrusive mare domes in other lunar regions highland domes and lunar cones has shown that the examined four mare dome fields display such a richness in spectral properties and 3d dome shape that the established representation remains valid in a more global context furthermore we estimate the physical parameters of dome formation for the examined domes based on a rheologic model each class of effusive domes defined in terms of spectral and morphometric properties is characterized by its specific range of values for lava viscosity effusion rate and duration of the effusion process for our data set we report lava viscosities between about 10 2 and 10 8 pas effusion rates between 25 and 600 m 3 s 1 and durations of the effusion process between three weeks and 18 years lava viscosity decreases with increasing r 415 r 750 spectral ratio and thus tio2 content however the correlation is not strong implying an important influence of further parameters like effusion temperature on lava viscosity

fluid geochemical transect in the northern apennines central northern italy fluid genesis and migration and tectonic implications chemical and isotopic characteristics of natural gas and thermal water discharges from the western back arc tyrrhenian sea across the apennine thrust belt to the po valley and adriatic coast foredeep basins in the northern apennines central northern italy reveal a large scale fluid motion in the upper crust both vertically and horizontally on the basis of gas compositions two different domains of rising fluids have been distinguished 1 co2 rich he poor 3he 4he high domain in the western peri tyrrhenian extensional sector 2 ch4 rich he rich 3he 4he low domain in the eastern adriatic compressional sector such gases rising from various depths are crossed by a huge lateral n2 rich water flow in the peri tyrrhenian sector of ca so4 hco3 meteoric derived waters that move in a regional wide aquifer hosted in a quite thick mesozoic carbonate series morphologically the co2 vents consist of mud basins with high gas rate emission where the rising fluids move upwards through diatremes on the other hand ch4 emissions seep out from typical mud volcanoes with a reduced gas flow rate where the fluid motion is likely related to saline diapir extrusions and the methane is mostly carried to the surface by the associated mud the two rising mechanisms described locate southwest and northeast of the apennine watershed respectively from a seismic point of view the ch4 domain in the thrust belt and foredeep areas is characterized by a large number of earthquakes indirectly pointing to a different rheological behavior of the terrains with respect to the more internal peri tyrrhenian area owing to the quite high thermal gradient of the latter the boundary of the brittle ductile crust in the peri tyrrhenian sector can be located at a 10 km shallow depth although the presence of several post orogenic basins would suggest widespread extensional tectonics in all areas west of the apennine watershed those located in the easternmost part display gas vents with typical crustal 3he 4he ratios as this ratio is very sensitive to deep fluids rising from the mantle we hypothesize that such basins at the foot of the apennines are not due to tensive stress as suggested by their morphological shape they are piggy back thrust top basins developed and evolved in a still acting compressive tectonic regime

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

formation of lunar mare domes along crustal fractures rheologic conditions dimensions of feeder dikes and the role of magma evolution abstract in this study we examine a set of lunar mare domes located in the hortensius milichius t mayer region and in northern mare tranquillitatis with respect to their formation along crustal fractures their rheologic properties the dimensions of their feeder dikes and the importance of magma evolution processes during dome formation many of these domes display elongated summit vents oriented radially with respect to major impact basins and several dome locations are also aligned in these preferential directions analysis of clementine uv vis and lunar prospector gamma ray spectrometer data reveals that the examined mare domes formed from low si basaltic lavas of high feo and low to moderate tio2 content based on their morphometric properties diameter height volume obtained by photoclinometric and shape from shading analysis of telescopic ccd images we derive rheologic quantities lava viscosity during eruption effusion rate duration of the effusion process magma rise speed and the dimensions of the feeder dikes we establish three rheologic groups characterised by specific combinations of rheologic properties and dike dimensions where the most relevant discriminative parameter is the lava viscosity the first group is characterised by 10 4 pa s 10 6 pa s and contains the domes with elongated vents in the milichius t mayer region and two similar domes in northern mare tranquillitatis the second group with 10 2 pa s 10 4 pa s comprises the very low aligned domes in northern mare tranquillitatis and the third group with 10 6 pa s 10 8 pa s the relatively steep domes near hortensius and in the t mayer region the inferred dike dimensions in comparison to lunar crustal thickness data indicate that the source regions of the feeder dikes are situated within the upper crust for six of the domes in northern mare tranquillitatis while they are likely to be located in the lower crust and in the upper mantle for the other examined domes by comparing the time scale of magma ascent with the time scale on which heat is conducted from the magma into the host rock we find evidence that the importance of magma evolution processes during ascent such as cooling and crystallisation increases with lava viscosity we conclude that different degrees of evolution of initially fluid basaltic magma are able to explain the broad range of lava viscosities inferred for the examined mare domes the spectral data reveal that differences in tio2 content may additionally account for the systematic difference in lava viscosity between the two examined lunar regions we show that the described mechanisms are likely to be valid also for other lunar mare domes situated near cauchy and arago regarded for comparison on the other hand we find for the gruithuisen and mairan highland domes that despite their inferred high lava viscosities of 10 8 10 9 pa s no significant magma cooling in the dike occurred during ascent supporting previous findings that the highland domes were formed during a specific phase of non mare volcanism by highly silicic viscous lavas

testing the relation between uv vis color and tio2 content of the lunar maria reflectance spectroscopy is important for placing lunar samples into a regional and global geologic context to this end the ultraviolet visible uv vis color ratio used to estimate the tio2 composition of mature mare basalts has been one of the most widely used spectral parameters in lunar exploration we examine the correlation between uv vis color and tio2 content using a combination of clementine lunar prospector and sample data to document the extent to which color is dependent upon tio2 examination of the remotely sensed data reveals that the correlation between uv vis ratio and tio2 composition is best represented by a sigmoidal trend rather than the canonical linear or curvilinear correlation with this information we are then able to evaluate between two models that propose different explanations for the relationship between uv vis color and tio2 the first model attributes the correlation between tio2 and uv vis color to spectrally neutral opaques i e ilmenite while the other emphasizes the effect of fe ti charge transfer in lunar glasses and dual scattering mechanisms between high and low ti basalts we do not find evidence in the spectral data to support the occurrence of fe ti charge transfer in lunar glass as the principal cause for color in high ti basalts the data also do not substantiate the existence of different scattering mechanisms e g volume v surface scattering between high and low tio2 basalts instead our analyses substantiate that the spectral effects of ilmenite exhibit a major influence over the uv vis ratio by including sample data we find that in addition to ilemenite tio2 content factors such as feo content ilmenite grain size modal abundance of plagioclase and the olivine to pyroxene ratio in a mare soils can influence the uv vis continuum these findings point to promising avenues of research that future uv vis spectral techniques can exploit in order to yield more accurate tio2 estimates and potentially additional petrologic information

surface morphology of domes in the marius hills and mons rumker regions of the moon from earth based radar data 1 clusters and coalesced complexes of domes represent a relatively rare landform within the extensive low relief lunar maria while they are typically spectroscopically similar to mare basalts emplaced by high volume low viscosity eruptions the large scale morphology of the domes is more consistent with slower emplacement and or more viscous magma we use new earth based radar data to study the decimeter to meter scale rock abundance at the surface and buried within the probing range of the radar signal of domes in the marius hills and mons rumker regions domes of the marius hills are characterized by high circular polarization ratio cpr values at 12 6 cm and 70 cm wavelength similar to the near rim ejecta deposits of young lunar craters like tycho areas of large ejecta fragments near the rim of meteor crater and blocky lavas such as sp flow in arizona we infer that a very rugged flow surface morphology associated with the original dome forming eruption rather than postemplacement modification exists beneath at most a few meters of regolith magmas with greater silica content than sampled lunar basalts are unlikely so the blocky structure of the dome forming lava must arise from some combination of compositional change effusion rate and or cooling effects not typically observed in basaltic landforms on the earth much of the 80 km diameter mons rumker has low backscatter and cpr at 12 6 cm wavelength relative to nearby mare terrain at 70 cm wavelength the northern and most of the southern parts of the complex are radar dark but there is a radar bright feature that extends from the central region eastward into oceanus procellarum we conclude that much of mons rumker is mantled by rock poor fine grained pyroclastic material the radar bright feature in the 70 cm map is detectable owing to some combination of greater roughness like the marius domes and thinner mantling cover

mapping the feo and tio2 content of the lunar surface with multispectral imagery the derivation of quantitative elemental concentrations from multispectral imaging of the moon has long been a goal of lunar remote sensing concentration maps at the spatial resolutions available from the recent clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust lucey et al 1995 presented a method for extracting the concentration of fe from multispectral imaging of the moon this paper examines and quantifies important aspects ofthat technique left unexamined by lucey et al which had the potential to severely limit its utility these aspects include the effects of maturity grain size mineralogy shading due to topography and the presence of glass we also present a new algorithm for derivation of tio2 from multispectral imaging of both mare and highland units we find that both techniques are only weakly sensitive to maturity and that they have about 1 wt accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by blewett et al 1997 we also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by pieters and coworkers and hapke and coworkers we find the view of hapke and coworkers to be more consistent with our observations using a global mosaic of clementine multispectral data and these element derivation algorithms we find that the global modal abundance of feo is 4 5 wt 1 wt and the global modal abundance of tio2 is 0 45 wt 1 wt

terrestrial mud volcanoes of the salse di nirano italy as a window into deeply buried organic rich shales of plio pleistocene age abstract the terrestrial mud volcanoes of the salse di nirano are situated in the northern apennines italy and were formed by the expulsion of mud water liquid hydrocarbons and gases predominantly methane ch 4 previous studies revealed that methane is consumed by microbial associations using the anaerobic oxidation of methane aom a process also occurring in marine settings this was supported by the presence of 13 c depleted biomarkers specific to sulfate reducing bacteria and archaea however the vast majority of biomarkers appeared to have other so far unexplained sources than microorganisms that in situ feed on hydrocarbon gases therefore lipid biomarker distributions of fluid samples from the salse di nirano mud volcanoes were revisited and compared to those extracted from organic rich shales from the underlying geological formations the organic chemical analyses of the mud volcano fluids revealed signals of various eukaryotic bacterial and archaeal organisms in addition to signals from higher plants specific bacterial dialkyl glycerol diethers dage in particular ai 15 ai 15 and 16 16 were found which putatively originate from sulfate reducing bacteria srb the presence of archaea is evidenced by archaeol and trace amounts of sn2 hydroxyarchaeol most biomarkers were not depleted in 13 c suggesting mainly non methane consuming source organisms organic chemical analyses of the plio pleistocene shales from the underlying geological formation revealed the same pattern for most of the bacterial and archaeal components the strong similarities between both samples suggest that the majority of the biomarkers in the emitted fluids in nirano originate from these marine organic rich deposits through which the fluids passed these biomarkers clearly obscure signals from microorganisms growing in situ in the mud volcanoes but the extent of this process is spatially and temporarily highly variable

spectral properties of the marius hills volcanic complex and implications for the formation of lunar domes and cones we have used multispectral data from the clementine uv visible camera to study the volcanic features of the marius hills complex and their comparison to other lunar domes and cones there are several mare units identified in the complex each with a unique ti content as indicated by their 415 750 nm value the domes in marius hills are spectrally identical to the mare plains of the complex supporting similar compositions in contrast most of the volcanic cones of the complex are lower in reflectance bluer in color and have weaker mafic absorptions than the mare and domes the spectral characteristics of the cones can best be explained by fine grained crystallization in the spatter that compose the cones other lunar cones such as mons esam in northern tranquillitatis have spectral properties similar to those at marius hills the rima parry cones and their associated dark mantle deposit appear redder with a stronger mafic absorption than the marius hills cones the cones isis and osiris in southern mare serenitatis the domes of rumker hills and several domes in northern mare tranquillitatis are spectrally similar to adjacent mare units the mairan and gruithuisen domes in northern oceanus procellarum have a feldspathic signature characteristic of highland material although they are redder and brighter than adjacent highland soils they appear to represent highland material that resembles domes rather than actual mare domes like those at marius and rumker hills the diversity of lunar volcanic features can best be explained by differences in accumulation rates and cooling of ejected clasts from various eruption styles mare domes may have formed at lower effusion rates thereby allowing lava to construct small shields with slopes 3 the steeper domes at marius hills require higher viscosities resulting from even lower effusion rates and enhanced crystallization in the magmas during the terminal stages of earlier eruptions that emplaced the mare cones like mons esam rima parry isis and osiris are aligned along linear rilles and are interpreted to result from degassing of near surface dikes in contrast the cones of marius hills show no linear alignment and may result from strombolian eruptions at the terminal stages of earlier effusive eruptions that emplaced the domes and mare in the complex

mechanisms of activity and unrest at large calderas large caldera collapses represent catastrophic natural events second only to large meteoritic impacts in addition some calderas are densely populated making the risk extreme even for moderate eruptions understanding caldera mechanisms unrest and the danger of eruption is therefore a crucial challenge for earth sciences several key features of caldera behaviour have yet to be fully understood through a combination of case studies and theoretical modelling the following topics are addressed in this volume the conditions required to produce and to release large volumes of magma erupted during caldera formation how magmatic feeding systems evolve before and after a caldera has formed the processes that limit the behaviour of precursors to eruptions how pre emptive precursors can be distinguished from those that drive unrest without an eruption and given that post collapse eruptions may occur across a wide area the optimum procedures for designing hazard maps and mitigation strategies

volcanism on the marius hills plateau observational analyses using clementine multispectral data we have studied the marius hills region and mapped the spectrally distinct flows present for the first time using photographic and clementine multispectral data the basalts on the plateau are varied in age and composition but are dominated by a high titanium eratosthenian basalt most likely from the same source as the flamsteed basalt further south the thickness of the basalts across the plateau is consistently greater than 120 m and is considerably thicker in some areas a lower limit of 5320 km3 of basalts has been erupted onto the plateau the domes and cones in the region do not appear to be related to any specific basalt or volcanic episode but occur at all levels in the stratigraphy that can be derived in the region the eruption conditions required to form these constructs indicate that they must represent a series of separate volcanic episodes occurring throughout the history of the plateau cones on the marius plateau are dominated by a strong glassy signature and often have an associated microlitic structure examples are shown of localized microlitic or glassy materials in regions where no cone is evident in the photographic data these features are proposed to represent short lived pyroclastic episodes that have deposited glassy and microlitic units on the plateau but have not been maintained for long enough to develop a cone the volcanic history of the marius hills region is extremely complex and most likely involved several separate episodes of volcanism with a large contrast in eruption styles and characteristics

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

compositional analyses of lunar pyroclastic deposits abstract the 5 band clementine uvvis data at 100 m pixel were used to examine the compositions of 75 large and small lunar pyroclastic deposits lpds and these were compared to representative lunar maria and highlands deposits results show that the albedo spectral color and inferred composition of most lpds are similar to those of low titanium mature lunar maria these lpds may have consisted largely of fragmented basalt with substantial components of iron bearing mafic minerals pyroxenes olivine and smaller amounts if any of volcanic glass several smaller lpds also show substantial highland components three classes of very large deposits can be distinguished from most lpds and from each other on the basis of crystallinity and possible titanium content of their pyroclastic components one class has spectral properties that are dominated by high titanium crystallized black beads e g taurus littrow a second consists of a mixture of high titanium glasses and beads with a higher glass bead ratio sulpicius gallus than that of taurus littrow and a third has a significant component of quenched iron bearing volcanic glasses aristarchus with possible moderate titanium contents although areally extensive these three classes of very large pyroclastic deposits compose only 20 of the 75 deposits studied 27 and eruption of such materials was thus likely to have been less frequent on the moon

lunar intrusive domes morphometric analysis and laccolith modelling abstract this study examines a set of lunar domes with very low flank slopes which differ in several respects from the frequently occurring lunar effusive domes some of these domes are exceptionally large and most of them are associated with faults or linear rilles of presumably tensional origin accordingly they might be interpreted as surface manifestations of laccolithic intrusions formed by flexure induced vertical uplift of the lunar crust or alternatively as low effusive edifices due to lava mantling of highland terrain or kipukas or structural features all of them are situated near the borders of mare regions or in regions characterised by extensive effusive volcanic activity clementine multispectral uvvis imagery indicates that they do not preferentially occur in specific types of mare basalt our determination of their morphometric properties involving a combined photoclinometry and shape from shading technique applied to telescopic ccd images acquired at oblique illumination reveals large dome diameters between 10 and more than 30 km flank slopes below 0 9 and volumes ranging from 0 5 to 50 km 3 we establish three morphometric classes the first class in1 comprises large domes with diameters above 25 km and flank slopes of 0 2 0 6 class in2 is made up by smaller and slightly steeper domes with diameters of 10 15 km and flank slopes between 0 4 and 0 9 and domes of class in3 have diameters of 13 20 km and flank slopes below 0 3 while the morphometric properties of several candidate intrusive domes overlap with those of some classes of effusive domes we show that a possible distinction criterion are the characteristic elongated outlines of the candidate intrusive domes we examine how they differ from typical effusive domes of classes 5 and 6 defined by head and gifford head j w gifford a 1980 lunar mare domes classification and modes of origin moon planets 22 235 257 and show that they are likely no highland kipukas due to the absence of spectral contrast to their surrounding these considerations serve as a motivation for an analysis of the candidate intrusive domes in terms of the laccolith model by kerr and pollard kerr a d pollard d d 1998 toward more realistic formulations for the analysis of laccoliths j struct geol 20 12 1783 1793 to estimate the geophysical parameters especially the intrusion depth and the magma pressure which would result from the observed morphometric properties accordingly domes of class in1 are characterised by intrusion depths of 2 3 3 5 km and magma pressures between 18 and 29 mpa for the smaller and steeper domes of class in2 the magma intruded to shallow depths between 0 4 and 1 0 km while the inferred magma pressures range from 3 to 8 mpa class in3 domes are similar to those of class in1 with intrusion depths of 1 8 2 7 km and magma pressures of 15 23 mpa as an extraordinary feature we describe in some detail the concentric crater archytas g associated with the intrusive dome ar1 and discuss possible modes of origin in comparison to the candidate intrusive domes terrestrial laccoliths tend to be smaller but it remains unclear if this observation is merely a selection effect due to the limited resolution of our telescopic ccd images an elongated outline is common to many terrestrial laccoliths and the putative lunar laccoliths while the thickness values measured for terrestrial laccoliths are typically higher than those inferred for lunar laccoliths but the typical intrusion depths are comparable

the laccolith stock controversy new results from the southern henry mountains utah domes of sedimentary strata at mount holmes mount ellsworth and mount hillers in the southern henry mountains record successive stages in the growth of shallow 3 to 4 km deep magma chambers whether the intrusions under these domes are laccoliths or stocks has been the subject of controversy according to g k gilbert the central intrusions are direct analogues of much smaller floored intrusions exposed on the flanks of the domes that grew from sills by lifting and bending of a largely concordant overburden according to c b hunt the central intrusions are cylindrical stocks sheathed with a zone of shattered sedimentary rocks and the small flanking sills and laccoliths grew laterally as tongue shaped masses from the discordant sides of these stocks new geologic mapping demonstrates that the sedimentary overburden now partially eroded from the domes was uplifted about 1 2 km at mount holmes 1 8 km at mount ellsworth and at least 2 5 km at mount hillers the radii of the domes are similar between 5 and 7 km the strata over the domes have a doubly hinged shape consisting of a concave upward lower hinge and a concave downward upper hinge a limb of approximately constant dip joins these two hinges and dips 20 at mount holmes 50 to 55 at mount ellsworth and 75 to 85 at mount hillers the distal portion of each dome is composed of a gently dipping peripheral limb 3 to 4 km long presumably underlain by sills and minor laccoliths although geologic cross sections and regional aeromagnetic data for the three domes are consistent with floored laccolithic central intrusions these data alone do not rule out the possibility of a stock at depth at mount hillers paleomagnetic vectors indicate that tongue shaped sills and thin laccoliths overlying the central intrusion were emplaced horizontally and were rotated during doming through about 80 of dip this sequence of events is not consistent with the emplacement of a stock and subsequent or contemporaneous lateral growth of sills and minor laccoliths growth in diameter of a stock from about 300 m at mount holmes to nearly 3 km at mount hillers as hunt suggested should have been accompanied by considerable radial shortening of the sedimentary strata and a style of folding which is not observed geologic and geophysical data and mechanical models support a laccolithic origin for the central magma chambers underlying the domes

extraction of lunar domes from chang e 2 data with new method abstract lunar domes which are distributed mainly in the lunar mare were generated by lunar volcanism several billion years ago in this context identifying lunar mare domes and studying their morphological properties enhances the study of lunar volcanism traditionally most lunar domes have been identified by manually analyzing images or topographic maps of the lunar surface this approach has identified several lunar domes in specific local areas to learn more about global lunar domes it is necessary to identify them from the global lunar mare in this paper we present a method of identifying lunar domes using chang e 2 data we demonstrate the identification of domes and analyze their morphological and geological properties

lunar gruithuisen and mairan domes rheology and mode of emplacement characteristics of the domes to estimate the yield strengths 10 5 pa plastic viscosities 10 9 pa s and effusion rates 50 m 3 s of the magmas which formed them these values are similar to those of terrestrial rhyolites dacites and basaltic andesites and support the hypothesis that these domes are an unusual variation of typical highlands and mare compositions the dikes which formed them are predicted to have had widths of 50 m and lengths of about 15 km the magma rise speed implied by this geometry is very low 7 10 5 m s and the reynolds number of the motion is 2 10 8 implying a completely laminar flow regime estimates of emplacement duration range from one to several decades these new calculations confirm the unusual nature of these features and support previous qualitative suggestions that they were formed from magmas with significantly higher viscosity than those typical of mare basalts index terms 5480 planetology solid surface planets volcanism 8450 5410 planetology solid surface planets composition 5460 planetology solid surface planets physical properties of materials 8429 volcanology lava rheology and morphology keywords moon volcanism domes

dynamics of magmatic intrusions in the upper crust theory and applications to laccoliths on earth and the moon 1 to understand the dynamics of shallow magmatic intrusions i propose a theoretical model of magma spreading laterally below an elastic crust nondimensionalization of the flow equation leads to the identification of characteristic scales for the intrusion while the characteristic intrusion length is controlled by the elastic response of the crust its characteristic thickness primarily depends on magma properties and injection rate three spreading regimes are identified and characterized by different morphologies as well as by scaling laws for thickness versus length and thickness versus time the first spreading regime is controlled by the elastic response of the crust and the shape of the flow is self similar when the time length and thickness become larger than an elastic time length and thickness scale the edges of the flow become steeper and the system transitions to a gravity current regime when the intrusion is thick enough to accommodate the pressure head the flow enters a regime of lateral propagation and keeps a constant thickness the intrusion shape in the elastic regime fits the observed shape of terrestrial laccoliths the elastic scaling law for intrusion thickness versus length fits observations of laccoliths at elba island italy and provides for a physical explanation for the observed relationship between length and thickness on terrestrial laccoliths laccoliths are predicted to form over short time scales depending on magma viscosity that vary between approximately a month to several years for felsic magmas on earth on the moon several elongated low slope domes have recently been identified as possibly formed by laccolith intrusions at depth although they are much larger than terrestrial laccoliths because the moon has a smaller gravity than on the earth a deeper magma source and a more mafic magma composition than for terrestrial laccoliths implying smaller pressure gradient and dike width lunar intrusions have a larger characteristic length and a smaller characteristic thickness after nondimensionalization the morphologies length versus thickness of terrestrial and inferred lunar laccoliths follow the same curve and are well fitted by the elastic scaling law this model thus explains the size discrepancy between terrestrial laccoliths and lunar low slope domes therefore low slope domes identified on the moon are good candidates for laccolith type intrusions at depth

magmatic intrusions and deglaciation at mid latitude in the northern plains of mars abstract on earth igneous rocks are generally affected by magmatic differentiation and the volume of intrusive bodies is considered to be 5 10 times larger than the volume of volcanic rocks in contrast in the case of mars the occurrence of olivine phyric basalts at gusev crater mcsween h y 2006 j geophys res planets 111 e10 e02s10 the primitive nature of at least four picritic shergottites grott m 2013 planet space sci 174 49 111 and the chemical composition of major volcanic provinces baratoux d toplis m j monnereau m gasnault o 2011 nature 472 338 341 suggest that primary melts of the mantle may have commonly reached the surface these observations together with sparse morphologic evidence of intrusions in comparison with other terrestrial planets raise the issue of the conditions for the formation and occurrence of sub surface zones of magma storage on mars in this respect a series of two types of young amazonian domes located at mid latitudes in western arcadia planitia east of phlegra montes previously interpreted as surface expressions of intrusive bodies farrand w h lane m d edwards b r yingst r a 2011 icarus 211 139 156 are examined here a fraction of the domes consist of upraised plain material whereas others distinguished by a massive core and a large aspect ratio could be partially exhumed intrusions or extrusions of viscous differentiated magma the latter interpretation is however not compatible with the mafic compositions inferred from orbital visible and near infrared spectroscopic observations the thicknesses and radii of both types of domes appear to be related through a power law relationship with exponents close to 1 or 5 4 these exponent values are not compatible with extrusive morphologies but are characteristic of intrusions magma below an elastic layer michaut c 2011 j geophys res 10 1029 2010jb008108 we conclude that all types of domes are intrusive bodies the large aspect ratios of some of these features may be reconciled with a mafic composition and a shallow emplacement a few hundred meters as well as a relatively large injection rate magma emplacement below an ice rich horizon that was subsequently removed offers a plausible scenario for their partial exhumation this scenario is supported by independent signs of ice removal and deflation events in the northern plains the formation of these intrusions appear therefore to be related to an unusual context of magma ascent below a thick and low density ice rich horizon

toward more realistic formulations for the analysis of laccoliths abstract the published laccolith analyses are based on the linear plate bending theory and the a priori assumption that the width of the laccolith is fixed this is not the case in an actual situation the dimension of the laccolith in the horizontal plane has to result from an additional matching condition at the separation lines the published analyses are generalized by dropping the a priori assumption that the width of the laccolith is prescribed by assuming that the magmatic pressure is not constant and by taking into consideration the vertical compressibility of the overburden plate and base in the contact region in order to determine the magnitude of the magmatic pressure a condition is postulated that equates the measured volume of the intruded magma in a laccolith with the corresponding analytical expression for the volume the obtained closed form solution appears to satisfy many of the intuitive expectations it was evaluated numerically and the results are presented as graphs it may be concluded that even very small laccoliths may exist provided the magmatic pressure is sufficiently larger than the overburden weight we also show the dependence of the laccolith size on its stratigraphic position the thicker the overburden h the larger the size of the laccolith for an overburden plate of given thickness the larger the volume v of the intruded magma the larger the laccolith width 2a and its height the paper concludes by discussing a published analysis for laccolith with flexible underburden and overburden it is shown that this analysis is based on a formulation that is of questionable validity

compositional gradients across mare highland contacts importance and geological implication of lateral transport observations of mixing across mare highland contacts using high resolution clementine data allow a new assessment of the relative importance of vertical versus lateral mass transport on the moon at least at mare highland contact we analyze mare highland contacts in the grimaldi orientale and fecunditatis basins and tsiolkovsky crater through image based nonlinear spectral mixture modeling of clementine ultraviolet visible uv vis light spectrometer multi spectral data the mare in these regions differ in ages but they are characterized by having simple geological contacts the symmetric distribution of mare and highland soil constituents across their geological contact indicates that lateral transport is more efficient than deep vertical transport during the formation of the observed mixing zones observations across the lunar limb with the clementine uv vis filters show that there is a stray light component of scattered light across high contrast albedo boundaries however the magnitude and spatial properties of scattered light do not significantly affect the nature of compositional boundaries determined here since repetitive meteorite bombardment governs lateral transport across the geological contacts and is a random process a stochastic model is developed to describe this lateral transport analysis of the power decay law for crater ejecta thickness indicates that the high velocity ejecta travels long distances and follows a 3 power decay law this results in an infinite variance which requires an anomalous diffusion model since a classical diffusion model would be invalid mathematical modeling supports this result where it is shown that classical diffusion produces a relatively poor fit to profiles of material abundance while the anomalous diffusion model fits the profiles adequately these results indicate that high velocity ejecta dominates the formation of the observed compositional gradients while the ejecta near the crater rim is relatively less important on the basis of these ejecta distributions and the assumption of random impact cratering we derive a relationship that can be used as an index for relative age dating of geological contacts as well as for investigating cratering rates

the origin of lunar concentric craters abstract lunar concentric craters are a unique class of impact craters because the interior of the craters contains a concentric ridge but their formation mechanism is unknown in order to determine the origin of concentric craters we examined multiple working hypotheses which include eight impact related and endogenic processes we analyzed data sets that originated from instruments onboard clementine kaguya and the lunar reconnaissance orbiter to characterize the morphology spatial distribution composition and absolute model ages of 114 concentric craters concentric craters contain five key properties 1 a concentric ridge 2 anomalously shallow floors 3 their occurrence is concentrated near mare margins and in mare pond regions 4 the concentric ridge composition is similar to the surrounding area and 5 concentric crater ages are eratosthenian and older these five key properties served as constraints for testing impact related and endogenic mechanisms of formation we find that most impact related hypotheses cannot explain the spatial and age distribution of concentric craters as for endogenic hypotheses we deduce that igneous intrusions are the likely mechanism that formed concentric craters because of the close relationship between concentric craters and floor fractured craters and the concentration of both features near mare highland boundaries and in mare ponds furthermore we observe that floor fractured craters are common at crater diameters 15 km whereas concentric craters are common at crater diameters 15 km produce floor fractured craters

coal and coal bearing strata recent advances and future prospects recent advances in coal geology are highlighted the increase in our knowledge of peat formation is emphasized and the application of hydrological models of mire systems to coal bearing strata is advocated the importance of coalification studies to the geological community as a whole should not be underestimated consideration of the original peat forming vegetation by coal geologists is advocated both conceptual and technical advances in coal geology are reviewed integration of different disciplines is likely to yield further insights into the study of coal and coal bearing strata

crater centered laccoliths on the moon modeling intrusion depth and magmatic pressure at the crater taruntius abstract many floor fractured craters on the moon show surface deformation like that seen over terrestrial laccoliths consequently terrestrial laccoliths provide one model for such crater modification this model directly relates surface deformation to the growth of a shallow crater centered intrusion and it estimates intrusion size and magma pressure it also yields a minimum estimate for intrusion depth maximum intrusion depths cannot be directly constrained but a range of likely intrusion depths can be derived with additional assumptions when the model is applied to the crater taruntius the surface record indicates an intrusion 30 km across and 1900 m thick the calculated excess magma pressure is 9 mpa 90 bar and the estimated intrusion depths range from 1 to 5 km if magma pressure reflects a hydrostatic magma column beneath taruntius these values suggest a total magma column length of 65 km during crater modification

the mons rumker volcanic complex of the moon a candidate landing site for the chang e 5 mission mons rumker is a large volcanic complex in oceanus procellarum on the moon and is a candidate landing site for china s chang e 5 sample return mission we conducted a comprehensive study of the topography geomorphology composition and stratigraphy of the mons rumker region with multi source remote sensing data in order to better understand the geology of the region and provide further support for the chang e 5 mission the results show that the rumker plateau stands 200 1300 m above the surrounding mare surface and 75 of the plateau has a slope of less than 3 at a baseline length of 30 m domes are the most prominent volcanic landforms in mons rumker and a total of 22 domes were identified and divided into two types that may represent different stages of volcanic activity spectral analyses indicated that mons rumker is covered by low ti basalt and the dominant mafic mineral is high calcium pyroxene though signs of mixing of highland materials and basalt have been found mons rumker has three main basalt units and their absolute model ages are 3 71 ga 3 58 ga and 3 51 ga respectively steep sided domes could be the youngest volcanic features on the plateau with indications that they were active until the eratosthenian a new geologic map of the study region was produced and used to interpret and discuss the geologic evolution of the region finally we propose two candidate landing sites for the chang e 5 mission