diviner lunar radiometer observations of cold traps in the moon s south polar region diviner lunar radiometer experiment surface temperature maps reveal the existence of widespread surface and near surface cryogenic regions that extend beyond the boundaries of persistent shadow the lunar crater observation and sensing satellite lcross struck one of the coldest of these regions where subsurface temperatures are estimated to be 38 kelvin large areas of the lunar polar regions are currently cold enough to cold trap water ice as well as a range of both more volatile and less volatile species the diverse mixture of water and high volatility compounds detected in the lcross ejecta plume is strong evidence for the impact delivery and cold trapping of volatiles derived from primitive outer solar system bodies

the use of multivariate statistics to elucidate patterns of floodplain sedimentation at different spatial scales floodplains are depositional features of riverine landscapes that display complex sedimentation patterns that are amenable to multi scale approaches we examined sedimentation in the lower balonne floodplain queensland australia at three different spatial scales the channel 103 km floodplain process zone 10 km and geomorphic unit 102 m scales and compared scale related patterns evident from stratigraphy with those evident from quantitative multivariate analysis three stratigraphic sequences were found in the lower balonne floodplain generally fining upward episodic fining upward and mud dominated stratigraphical analysis revealed the detailed character of sedimentary sequences embedded within the scale patterns derived from multivariate analysis multivariate statistical analyses of a range of textural and geochemical data revealed different patterns of floodplain sedimentation at each scale at the channel scale sediment texture and geochemistry were more heterogeneous in the culgoa river than in briarie creek at the floodplain process zone scale clear patterns of sediment texture and geochemistry were observed along the upper mid and lower floodplain process zones of briarie creek but not along the culgoa river at the geomorphic unit scale clear patterns of sediment texture and geochemistry were observed among the bank buried channel and flat floodplain units of the culgoa river but were not as clear in briarie creek recognition of rivers as hierarchically organized systems is an emerging paradigm in river science our study supports this paradigm by demonstrating that different sedimentation patterns occur at different scales to reveal a hierarchically organized floodplain environment copyright 2006 john wiley sons ltd

controls on fan development evidence from fan morphometry and sedimentology sierra nevada se spain abstract we have studied the morphology and the morphometric relations between alluvial fans and drainage basins in a bajada system including more than 20 coalescent fans developed since the late pleistocene as a result of the recent uplift of the sierra nevada betic cordillera spain three allocycles of tectonic origin were recognised across which there is a clear evolution from debris flow to sheet flow dominated fans in connection with a decrease in the volume of fines available in the source areas the larger volume of accommodation space created by higher tectonic subsidence in the northern sector favoured vertical accumulation of sediment with the appearance of less elongated fans in the rest of the system where subsidence is less more elongated fans appear with the development of incised channels and irregular distribution of sediment in depositional lobes this involves the appearance of markedly asymmetric transverse profiles as well as lengthy recurrence between the sedimentation events on particular sectors of the fans where headward eroding gullies develop the lithology of the source area where intensely fractured rocks are found is responsible for an important sediment supply and a significant degree of clast sorting from the source area consequently a weak longitudinal trend in particle size can be recognised which influences the predominance of longitudinal constant slope profiles and anomalous relations between both fan area and fan slope and their drainage areas recent intense tectonic activity has caused the appearance of abnormally low slopes in upper sectors of some catchments where mass flows are trapped and the fans present a subsequently higher proportion of sheet flows recent piracy phenomena can be recognised in some of the drainage basins which indicate rejuvenation of the source area in which case the fan presents a rapid increase in the proportion of mass flows with the development of a segmented longitudinal profile due to the recent nature of the processes the morphometric relations in the fan fed by the basin affected by capture do not coincide with the other fans in the area

stability of polar frosts in spherical bowl shaped craters on the moon mercury and mars following svitek martian water frost control of global distribution by small scale processes ph d thesis california institute of technology 1992 analytic solutions are presented for the effective albedo the effective emissivity and the radiative equilibrium temperature in the shadowed portions of a spherical bowl shaped crater the model assumes that the surface is a lambert scatterer with visual albedo and infrared emissivity each independent of wavelength across their respective spectral ranges absorption emission and multiple scattering from the walls of the crater are treated rigorously to all orders for airless bodies whose surfaces are in radiative equilibrium all shadowed portions of any individual crater have the same temperature whose value depends on four quantities the insolation product of the solar constant and the sine of the solar elevation angle the depth diameter ratio of the crater the visual albedo and the infrared emissivity as long as the crater is deep enough to have shadows the lowest temperatures are for the shallowest crater those with the smallest depth diameter ratio the model is applied first to the moon and mercury using a depth diameter ratio of 0 2 which is typical of the lunar highlands according to pike geophys res lett 1 291 294 1974 in impact and explosion cratering roddy et al eds pp 489 509 pergamon new york 1977 for mercury and the moon temperatures in shadows in polar craters are below 102 k so the sublimation rate of water ice calculated according to the model of watson et al j geophys res 66 3033 3015 1961 is less than 1 cm per byr the latitudinal extent of the cold zone on the moon is greater than that on mercury although temperatures at the poles of the two planets are similar the other application is to polar frosts on mars illuminated water frosts in radiative equilibrium grow rougher because the average temperature of a depression is greater than that of flat ground subliming co 2 frosts which are always at the same temperature grow rougher at low solar elevation angles because the heat flux absorbed by a depression is greater than that for a flat surface at high insolation rates high sun near perihelion the average heat flux to a depression is less than for a flat surface the latter evaporates faster which makes the average surface smoother and leads to a high average albedo this behavior helps explain the fact that the south co 2 cap which receives its greatest insolation near perihelion has a higher effective albedo and therefore can survive the summer whereas the north co 2 cap has a lower effective albedo and disappears each year around summer solstice

a large mammal site in a meandering fluvial context fonelas p 1 late pliocene guadix basin spain sedimentological keys for its paleoenvironmental reconstruction abstract the fonelas p 1 large mammal site is located stratigraphically in the youngest unit late pliocene pleistocene of the endorheic fill of the guadix basin betic cordillera at the site location this unit is represented by fluvial sediments of the basin s axial drainage system the general succession of the site consists of stacked fining upward cycles basically beginning with gravel and or sand filling a meandering channel and concluding with floodplain mud and carbonate each of the cycles is made up of four facies associations determined by sedimentological analysis of the sections measured in the paleontological excavation of the site these associations correspond to sedimentation in definite areas of the fluvial system a filling of a sinuous channel at maximum activity b levee deposits c abandoned channel and d floodplain in the cycle in which the site is located there is a fifth association e where the main fossil concentration is found fonelas p 1 this is a facies bioturbated by mammals moving over sediments of the abandoned channel association c by space time reconstruction of the fluvial environments we can infer that the morphological depression caused by a meander abandonment due to chute cut off was used as a hyena den the animal settlement ended when overflow from the laterally migrating active channel began to bury the abandoned meander with floodplain sediments

stratigraphic architecture and alluvial geoarchaeology of an ephemeral fluvial infilling climatic versus anthropogenic factors controlling the holocene fluvial evolution in southeastern spain drylands abstract two stages of depositional high discharge fluvial environments are recorded in the infilling of a rock shelter in a canyon of the segura river namely 1 first stage aggradational alluvial gravels in the lower part interpreted as braided channel bars seventh millennium to 2030 cal bc and 2 second stage slackwater flood deposits in the upper part between 2030 cal bc and after 900 ad during a stage of main channel incision reconstructed flood discharges for the second stage were a minimum of 700 m 3 s extreme palaeofloods that inundated the cave from the canyon inlet were successively higher and are correlated to quick rising flash floods the characteristics of cultural remains preserved by flood deposits reveal long periods of human cave occupation and passage through the canyon without extreme floods occurring these long periods of low discharge fluvial flow punctuated by catastrophic flash floods are linked to a torrential fluvial regime the torrential regime is the current hydrologic and climatic scenario in the streams of semi arid southeastern spain it is discusses the climatic versus anthropogenic factors affecting the fluvial development we conclude that the archaeo fluvial record of the pozo rock shelter indicates that the present day semi arid conditions of the southeastern spain drylands extend back to circa 4000 yr bp methodologically the combination of fluvial palaeohydrology and geoarchaeology appears to be a robust tool to reconstruct long term holocene climate changes

lunar surface roughness derived from lro diviner radiometer observations abstract sunlit and shaded slopes have a variety of temperatures based on their orientation with respect to the sun generally greater slope angles lead to higher anisothermality within the field of view this anisothermality is detected by measuring changing emitted radiance as a function of viewing angle or by measuring the difference in brightness temperatures with respect to observation wavelength thermal infrared measurements from the lunar reconnaissance orbiter diviner radiometer were used to derive lunar surface roughness via two observation types 1 nadir multispectral observations with full diurnal coverage and 2 multiple emission angle targeted observations measurements were compared to simulated radiance from a radiative equilibrium thermal model and gaussian slope distribution model nadir observations most closely match a 20 rms slope distribution and multiple emission angle observations can be modeled using 20 35 rms slope distributions limited sampling of the lunar surface did not show any clear variation in roughness among surface units two dimensional modeling shows that surfaces separated by distances greater than 0 5 5 mm can remain thermally isolated in the lunar environment indicating the length scale of the roughness features non equilibrium conditions are prevalent at night and near sunrise and sunset preventing the use of the equilibrium thermal model for roughness derivations using data acquired at these local times multiple emission angle observations also show a significant decrease in radiance at high emission angles in both daytime and nighttime observations and hemispherical emissivity is lower than is apparent from nadir observations these observations and models serve as a basis for comparison with similar measurements of other airless bodies and as an initial template for the interpretation of tir measurements acquired under a variety of geometric conditions

facies architecture geochemistry and palaeoenvironmental reconstruction of a barrage tufa reservoir analog betic cordillera s spain continental carbonates are currently of high interest for the oil and gas industry as they have proved to be good reservoir rocks in brazil and angola offshore oil fields in this article a tufa system in which continental carbonates formed mainly in the pliocene rambla becerra tufa system guadix basin betic cordillera s spain is described in detail and a model proposed for its formation and evolution through time several stages of tufa growth have been identified in the field intercalated between stages of progradation of alluvial fan sediments the tufa system connects laterally with the fluvial system developed in the axial valley of the guadix basin during the pliocene and the pleistocene indicating that the tufa formation was coetaneous with the periods of lateral expansion of the fluvial system floodplain that in previous works have been interpreted as more humid stages and potentially warmer the absence of extraclasts in the tufa sediments points to the low activity of the alluvial fans during the tufa formation and therefore supports the idea that the main tufa growth happened during more humid stages and the alluvial fans developed further during the more arid periods which is consistent with other recent findings in the guadix basin the tufa growth is represented by four main stages the second one bearing the best example to study as a potential reservoir analog as the main outcrop is a discrete body with a specific geometry and facies distribution this main outcrop is a mound shaped tufa build up formed by prograding sigmoids of clastic tufa interpreted as the ramp like buttresses developed after a barrage in a barrage tufa system from a preliminary isotopic study of the carbonates forming the barrage tufa system and by comparison with other tufas and travertines the oxygen and carbon stable isotopes point to an intermediate situation between a palustrine tufa and a travertine this information when added to the sedimentological data supports the idea that water feeding the tufa system probably had different sources a meteoric one coinciding with the surface runoff and a groundwater one probably in the form of springs fed by groundwater from the nearby aquifers that still exist in the mesozoic carbonates that form the external zones of the betic cordillera in the area

effects of orbital evolution on lunar ice stability 1 many regions near the lunar poles are currently cold enough that surface water ice would be stable against sublimation losses for billions of years however most of these environments are currently too cold to efficiently drive ice downward by thermal diffusion leaving impact burial as the primary means of protection from surface loss processes in this respect most of the present near surface thermal environments on the moon may actually be quite poor traps for water ice this was not always the case long term orbital changes have dramatically altered the lunar polar thermal environment we develop a simple model of the evolution of the lunar orbit and spin axis to examine the thermal environments available for volatile deposition and retention in the past our calculations show that some early lunar polar environments were in the right temperature regime to have collected subsurface ice if a supply were available however a high obliquity period which occurred when the moon was at about half its present distance from the earth would either have driven this ice out into space or deep into the lunar subsurface since that time as the lunar obliquity has slowly decreased to its present value environments have undergone their own thermal evolution and each of the current cold traps experienced a period when they were most efficient at thermally burying ice we examine the thermal history of a lunar polar crater to provide a framework for examining other processes effecting volatiles in the moon s near surface cold traps

channel migration patterns and related sequences in some alluvial fan systems abstract the pendular displacement of a channel system consisting of an area of higher channel density trunk channel zone on both sides of which channel density progressively decreases secondary channel zone can under favourable subsidence conditions lead to the development of alluvial fans characteristic sequences are found in these fans depending on their position in the sedimentary body a marginal position in the fan is thus recognized by the superposition of fining and thinning upwards ftu cycles the upper part of which is made up of important thicknesses of overbank fines all the backsets of bars dipping in the same direction towards the centre of the cone on the other hand a central position is characterized by a higher number of ftu cycles which are incomplete due to erosion of the upper parts corresponding to the higher concentration of overbank fines and the backsets in each cycle dip alternately in opposite directions the displacement of the channel system in a constant direction may be caused by the preferential accumulation of bars on one of the banks of the channel the change in migratory direction giving rise to the pendular movement is caused by the trunk channel reaching the basin margin or the sedimentation area of an adjoining fan palaeogeographic reconstructions of fans using this technique contribute to the analysis of ancient basins small radius fans with a high sweep angle as are characteristic of basin margins subjected to a low sediment supply subsidence ratio ss sb whereas large radius fans with a low as characterize periods with a high ss sb ratio on the basin margin this model can be applied in economic geology studies as the location of an ancient cone permits delimitation of the axial strip with a higher proportion of coarse highly porous channelled facies and the marginal sectors where thick layers of less porous overbank fines are intercalated we here present the example of the alluvial fans in the guadix fm betic cordillera spain which lie on a basin margin ese where the ss s b ratio increased progressively throughout the lower pliocene the detailed analysis of palaeocurrents on the basis of different criteria throughout the arroyo de gor section helps to locate more precisely and confirm the palaeogeographical distribution of the pliocene cone as deduced from sequential analysis

the role of diagenesis and depositional facies on pore system evolution in a triassic outcrop analogue se spain abstract this study aims at unravelling the diagenetic history and its effect on the pore system evolution of the triassic redbeds exposed in se spain tibem 1 an outcrop analogue of the tagi trias argilo greseux inferieur reservoir berkine ghadames basin algeria similar climatic base level and tectonic conditions of aforementioned alluvial formations developed analogue fluvial facies stacking patterns furthermore interplay of similar detrital composition and depositional facies in both formations resulted in analogue early diagenetic features petrographic observations indicate lithic subarkosic floodplain facies and subarkosic braidplain facies compositions which are considered suitable frameworks for potential reservoir rocks primary porosity is mainly reduced during early diagenesis through moderate mechanical compaction and formation of k feldspar overgrowth gypsum dolomite and phyllosilicate cements early mesodiagenesis is testified by low chemical compaction and quartz cementation telodiagenetic calcite filling fractures and k feldspar dissolution determined the final configuration of analysed sandstones mercury injection capillary pressure technique reveals overbank deposits in the floodplain as the least suitable potential reservoirs because of their lowest open porosity op k k 95 md and greater thickness and lateral continuity so being considered the best potential reservoir the accurate estimation of tibem microscale attributes can provide important input for appraisal and enhanced oil recovery performance in tagi and in others reservoirs consisting on similar fluvial sandy facies

mapping and characterization of non polar permanent shadows on the lunar surface abstract we present the first globally complete inventory of permanent shadows on the lunar surface that are detectable with the current global instrument datasets including discovery of regions with persistent shadows over geologic time periods as close to the equator as 58 of latitude these results were obtained through application of a ray tracing technique to the latest global topographic datasets from the lunar reconnaissance orbiter our analysis reveals that 13 361 km2 of surface in the northern hemisphere and 17 698 km2 in the southern hemisphere are permanently shadowed we present maps showing the locations of all the permanent shadows detectable using these datasets then turn our focus toward the permanent shadows farthest from the poles each permanent shadow on the equator side of 65 of latitude is shown in detail surface brightness temperature data derived from the diviner mid infrared radiometer on board the lunar reconnaissance orbiter have been analyzed for four of these locations and found to have mid day temperatures 75 120 k less than nearby comparison locations that experience direct daytime illumination in some cases the permanently shadowed locations have nighttime temperatures 10 25 k lower than surroundings the temperature results support our finding that these non polar craters are permanently shadowed the surface brightness temperature results also raise interesting questions about their ability to cold trap volatiles discovery of these non polar permanently shadowed regions increases possible locations of water resources and high priority exploration targets on the moon

structure of some lower old red sandstone conglomerates kincardineshire scotland deposition from late orogenic antecedent streams a thick succession of early lower old red sandstone ors conglomerates and subordinate sandstones are preserved in a small fault bounded basin in the ne midland valley of scotland the conglomerates associated with the northern margin of this basin are distinguished by a complex provenance which involved both reworking of existing gravels and addition of contemporary volcanic and plutonic detritus this may explain their characteristic bimodal texture deposition was in large probably permanent low sinuosity channels with evidence for both periods of uniform high stage flow and repeated flow stage fluctuations variable palaeoflows in the basal part of the succession suggest deposition on wet type alluvial fans supplied by feeder channels with a high sediment and water discharge the thickness of the succession the poorly developed cyclothems despite active syndepositional faulting evidence for rapid aggradation and the inferred scale of channel bars and coarsening upward units produced by bar migration suggest the basin may have been externally drained transverse antecedent streams are invoked to account for the structure of alluvium during the early devonian central scotland lay close to the boundary between regions suffering scandian orthogonal shortening and acadian strike slip shear the tectonic controls which governed the preservation of early lower ors sediments may have been largely uncoupled from those determining the supply and dispersal of the sediment

thermal stability of volatiles in the north polar region of mercury thermal models for the north polar region of mercury calculated from topographic measurements made by the mercury surface space environment geochemistry and ranging messenger spacecraft show that the spatial distribution of regions of high radar backscatter is well matched by the predicted distribution of thermally stable water ice messenger measurements of near infrared surface reflectance indicate bright surfaces in the coldest areas where water ice is predicted to be stable at the surface and dark surfaces within and surrounding warmer areas where water ice is predicted to be stable only in the near subsurface we propose that the dark surface layer is a sublimation lag deposit that may be rich in impact derived organic material

the thermal stability of water ice at the poles of mercury recent radar observations of mercury have revealed the presence of anomalous radar reflectivity and polarization features near its north and south poles thermal model calculations show that despite mercury s proximity to the sun the temperatures of flat low reflectivity surfaces at mercury s poles are not expected to exceed 167 kelvin the locations of the anomalous polar radar features appear to be correlated with the locations of large high latitude impact craters maximum surface temperatures in the permanently shadowed regions of these craters are expected to be significantly colder as low as 60 kelvin in the largest craters these results are consistent with the presence of water ice because at temperatures lower than 112 kelvin water ice should be stable to evaporation over time scales of billions of years

postdepositional enrichment of uranium in sediment from the bering sea abstract deep sea sediments were collected from the northern north pacific and the bering sea and separated into hcl soluble and hcl insoluble fractions these sediments were analyzed for their uranium and thorium concentrations and 234 u 238 u activity ratios by alphaspectrometry the mean concentration of total uranium in the oxic northern north pacific sediment was relatively low 1 25 ppm and showed little variation with sediment depth the concentration of total uranium in the surface sediment of the bering sea basin was also low 0 85 ppm similar to those of the northern north pacific sediment but it was higher 2 36 ppm in the strongly reducing sediment below 40 cm this increase in uranium concentration with depth is ascribed to higher quantities of hcl soluble uranium it is suggested that uranium diffuses through interstitial water and is postdepositionally precipitated during early diagenesis in the subsurface reducing environment a postdepositional precipitation rate of uranium in the bering sea basin sediment was estimated to be 28 g cm 2 103 yr 1 in the reducing bering sea basin sediment the concentration of total uranium in the layers enriched in manganese carbonate was 1 68 ppm which was slightly less than that of the other normal deep layer this depletion of uranium may be due to dilution with volcanic material of coarser texture

quantitative subsidence uplift analysis of the bajo segura basin eastern betic cordillera spain tectonic control on the stratigraphic architecture the bajo segura basin is located in the eastern betic cordillera at present connected with the mediterranean sea to the east it has a complete stratigraphic record from the tortonian to the quaternary which has been separated into six units bounded by unconformities this paper is concerned with the northern edge of the basin controlled by a major strike slip fault the crevillente fault zone cfz where the most complete stratigraphic successions are found the results obtained summarised below are based on an integrated analysis of the sedimentary evolution and the subsidence uplift movements unit i early tortonian is transgressive on the basin basement and is represented by ramp type platform facies organised in a shallowingupward sequence related to tectonic uplift during the first stages of movement along the cfz unit ii lower late tortonian consists of shallow platform facies at bottom and pelagic basin facies at top forming a deepening upward sequence associated with tectonic subsidence due to sinistral motion along the cfz unit iii middle late tortonian is made up of exotic turbiditic facies related to a stage of uplift and erosion of the southern edge of the basin unit iv upper late tortonian consists of pelagic basin facies at bottom and shallow platform facies at top defining a shallowing upward sequence related to tectonic uplift during continued sinistral movement on the basin bounding fault units v latest tortonian messinian and vi pliocene pleistocene p p consist of shallowing upward sequences deposited during folding and uplift of the northern margin of the basin no definitive evidence of any major eustatic sea level fall associated with the messinian salinity crisis has been recorded in the stratigraphic sections studied q 2001 elsevier science b v all rights reserved

two dimensional distribution of volatiles in the lunar regolith from space weathering simulations 1 we present simulations of space weathering effects on ice deposits in regions of permanent shadow on the moon these monte carlo simulations follow the effects of space weathering processes on the distribution of the volatiles over time the model output constrains the coherence of volatile deposits with depth lateral separation and time the results suggest that ice sheets become broken and buried with time as impacts begin to puncture an initially coherent surficial ice sheet small areas with a deficit of ice compared to surrounding areas are formed first as time progresses holes become prevalent and the anomalous regions are local enhancements of ice concentration in a volume the 3 d distribution is also heterogeneous because the ice is buried to varying depths in different locations analysis of the coherence of ice on 10 cm scales predicts that putative ice sheets in anomalous radar craters are 1000 myr old for future in situ analysis of cold trap volatiles a horizontal range of 10 m is sufficient to acquire surface based measurements of heterogeneously distributed ice these results also support previous analyses that mercury s cold traps are young

sedimentary basin destruction inferred from the evolution of drainage systems in the betic cordillera southern spain the guadix continental basin developed during the uppermost miocene the pliocene and the pleistocene one axial fluvial system and two transverse systems are interpreted in its alluvial infill in addition there are areas of lacustrine sedimentation permanent in the eastern sector and ephemeral in the western part of the basin from a sedimentological point of view the holocene drainage network shows significant similarities with that which occupied the ancient basin although there are some differences in location these provide information about the processes involved in the transformation of the sedimentary basin into an erosional basin with external drainage most of the data seem to indicate that the capture of drainage from the guadix basin by the guadalquivir river was accelerated principally by tectonic processes related to a recent uplift of a sector of the betic cordillera together with the disappearance of subsident points of the basin the high rate of holocene erosion is partially conditioned by the type of sediment deposited in the basin a low degree of lithification textural heterogeneity etc in comparison with the basement and mainly by the position of the ancient basin in relation to the new relative base level located almost 500 m lower than the position actually occupied by the pleistocene relative base level of the basin

thick ice deposits in shallow simple craters on the moon and mercury permanently shadowed regions near the poles of mercury and the moon may cold trap water ice for geologic time periods in past studies thick ice deposits have been detected on mercury but not on the moon despite their similar thermal environments here we report evidence for thick ice deposits inside permanently shadowed simple craters on both mercury and the moon we measure the depth diameter ratio of approximately 2 000 simple craters near the north pole of mercury using mercury laser altimeter data we find that these craters become distinctly shallower at higher latitudes where ice is known to have accumulated on their floors this shallowing corresponds to a maximum infill of around 50 m consistent with previous estimates a parallel investigation of approximately 12 000 lunar craters using lunar reconnaissance orbiter data reveals a similar morphological trend near the south pole of the moon which we conclude is also due to the presence of thick ice deposits we find that previously detected surface ice deposits in the south polar region of the moon are spatially correlated with shallow craters indicating that the surface ice may be exhumed or linked to the subsurface via diffusion the family of lunar craters that we identify are promising targets for future missions and may also help resolve the apparent discrepancy between the abundance of frozen volatiles on mercury and the moon ice deposits up to around 50 m thick infill some craters near the moon s south pole and mercury s north pole as inferred from the poleward shallowing of simple craters

alluvial and fluvial fans on saturn s moon titan reveal processes materials and regional geology fans landforms that record the storage and transport of sediment from uplands to depositional basins are found on saturn s moon titan a body of significantly different process rates and material compositions from earth images obtained by the cassini spacecraft s synthetic aperture radar reveal morphologies roughness textural patterns and other properties consistent with fan analogues on earth also viewed by synthetic aperture radar the observed fan characteristics on titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres exposing topographic variations and influences on fan formation there is evidence for a range of particle sizes across proximal to distal fan regions from c 2 cm or more to fine grained which can provide details on sedimentary processes some features are best described as alluvial fans which implies their proximity to high relief source areas while others are more likely to be fluvial fans drawing from larger catchment areas and frequently characterized by more prolonged runoff events the presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour fans join the growing list of landforms on titan derived from atmospheric and fluvial processes similar to those on earth strengthening comparisons between these two planetary bodies

near surface ice on mercury and the moon a topographic thermal model abstract a thermal model that can be easily adapted to craters of arbitrary shape is developed and applied to high latitude impact craters on mercury and the moon chao meng fu crater at 87 5 l on mercury an unnamed bowl shaped crater at 86 7 l on mercury and peary crater at 88 6 l on the moon for an assumed input topography and grid of surface elements the model computes for each element the irradiation from direct insolation and reflected and emitted radiation from other elements taking into account shadowing by the walls of the crater partial obscuration of the solar disk near the poles and the diurnal orbital and seasonal cycles temperatures are computed over the surface grid as functions of depth and time from the surface to a specified depth and over the pertinent astronomical cycles including the effects of direct and indirect surface irradiation infrared radiation heat conduction and interior heating vapor fluxes and ice recession times are computed as functions of ice depth over the surface grid temperatures profiles vapor fluxes and ice recession times were computed for flat surfaces not associated with craters near the poles of mercury and the moon it was found that water ice could have existed throughout geologic time within the maximum radar detection depth of recent observation of mercury j k harmon and m a slade 1992 science 258 640 643 poleward of 87 88 l on mercury and poleward of 73 l on the moon for chao meng fu crater it was found that 40 of the crater floor is permanently shadowed from direct solar insolation while the remainder of the crater floor is periodically illuminated by a partially obscured sun temperatures at the upper levels of the south wall can slightly exceed 550 k surface temperatures in the permanently shadowed region of the crater floor are under 130 k which could have allowed water ice to exist throughout geologic time within the radar detection depth of recent observation of mercury for the small bowl shaped crater on mercury it was found that most of the crater is permanently shadowed from direct solar radiation except for a narrow semicircular band bordering the north rim however temperatures in the permanently shadowed region periodically reach a maximum near 315 k due to efficient heating of the small crater by thermal emission and reflection from the small sunlit region which periodically reaches temperatures exceeding 630 k water ice could not have existed throughout geologic time anywhere in this crater within the radar detection depth for peary crater on the moon the entire crater floor is permanently shadowed from direct solar insolation with maximum temperatures under 120 k the upper level of the north wall periodically reaches a maximum temperature near 310 k the low temperatures on the crater floor would have allowed water ice to exist near the surface throughout geologic time provided that the moon s obliquity was always as low as it is at present

the plio pleistocene evolution of the southern middle atlas fault zone smafz front of morocco the south middle atlas front constitutes a northeast trending shear zone located north of the neogene missour basin and east of the taza guercif basin this paper analyses the southern middle atlas fault zone smafz deformation since the pliocene the set of structures observed suggests that reverse and thrust faulting along the central part of the smafz are combined with left lateral slip along n s striking faults of its south western termination and right lateral faulting along e ne striking faults of the east northeast termination thrusts and oblique thrust related anticlines of the two lateral ramps partly accommodate north west directed motion of the african plate the thrusts probably resulted from rejuvenation of jurassic normal faults they were active during the upper miocene pliocene and the pleistocene the geometries of positive inversion structures and buttressing effects are clearly dependent on the geometry and sedimentology of the original basin controlling fault system and on the presence of a decollement level field mapping is integrated with landsat imagery and a digital elevation model to investigate the morphotectonic evolution of the south eastern range front of the middle atlas geomorphological features provide significant information on the processes that govern lateral propagation of active anticlines both suggest that the deformation front may have been active since pliocene

high resolution radar imaging of mercury s north pole abstract the recently upgraded arecibo s band 12 6 cm radar was used to make delay doppler images of mercury s north polar region where earlier observations had shown strong echoes from putative ice deposits in craters the image resolution of 1 5 3 km is a substantial improvement over the 15 km resolution of the older arecibo images j k harmon et al 1994 nature 369 213 215 the new observations confirm all the original polar features and reveal many additional features including several at latitudes as low as 72 75 n and several from craters less than 10 km in diameter all of the new features located on the mariner imaged side of the planet can be matched with known craters or other shaded areas we find the north pole to be located 65 km from the original mariner based pole and 15 km from the new mariner based pole of m s robinson et al 1999 j geophys res 104 30 847 30 852 the improved resolution reveals fine structure in the radar features and their respective host craters including radar shadowing highlighting by central peaks and rim walls rim terracing and preferential concentration of radar bright deposits in shaded southern floor areas the radar features high brightness circular polarization inversion c 1 25 and confinement to regions permanently shaded from direct sunlight are all consistent with volume scattering from a cold trapped volatile such as clean water ice the sizes and locations of most of the features show good agreement with the thermal model of a r vasavada d a paige and s e wood 1999 icarus 141 179 193 for insulated buried water ice although the problems of explaining radar features in small craters and the rapid burial required at lower latitudes suggest that other factors may be suppressing ice loss after emplacement

how dielectric breakdown may contribute to the global weathering of regolith on the moon abstract space weathering is an important process on airless bodies and it must be considered when interpreting data from planetary missions previous work has shown that solar energetic particles may cause dielectric breakdown in regolith within permanently shadowed regions near the poles of the moon here we predict that dielectric breakdown weathering could have melted and or vaporized 2 9 of gardened i e thoroughly mixed regolith at the equator and 5 11 near the poles if so then 3 10 of all gardened regolith on the moon may have experienced dielectric breakdown and this process must be considered when analyzing remote sensing data or soil samples returned by the luna and apollo missions

stability of ice on the moon with rough topography abstract the heat flux incident upon the surface of an airless planetary body is dominated by solar radiation during the day and by thermal emission from topography at night motivated by the close relationship between this heat flux the surface temperatures and the stability of volatiles we consider the effect of the slope distribution on the temperature distribution and hence prevalence of cold traps where volatiles may accumulate over geologic time we develop a thermophysical model accounting for insolation reflected and emitted radiation and subsurface conduction and use it to examine several idealized representations of rough topography we show how subsurface conduction alters the temperature distribution of bowl shaped craters compared to predictions given by past analytic models we model the dependence of cold traps on crater geometry and quantify the effect that while deeper depressions cast more persistent shadows they are often too warm to trap water ice due to the smaller sky fraction and increased reflected and reemitted radiation from the walls in order to calculate the temperature distribution outside craters we consider rough random surfaces with a gaussian slope distribution using their derived temperatures and additional volatile stability models we estimate the potential area fraction of stable water ice on earth s moon for example surfaces with slope rms 15 corresponding to length scales 10 m on the lunar surface located near the poles are found to have a 10 exposed cold trap area fraction in the subsurface the diffusion barrier created by the overlaying regolith increases this area fraction to 40 additionally some buried water ice is shown to remain stable even beneath temporarily illuminated slopes making it more readily accessible to future lunar excavation missions finally due to the exponential dependence of stability of ice on temperature we are able to constrain the maximum thickness of the unstable layer to a few decimeters

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

bright and dark polar deposits on mercury evidence for surface volatiles measurements of surface reflectance of permanently shadowed areas near mercury s north pole reveal regions of anomalously dark and bright deposits at 1064 nanometer wavelength these reflectance anomalies are concentrated on poleward facing slopes and are spatially collocated with areas of high radar backscatter postulated to be the result of near surface water ice correlation of observed reflectance with modeled temperatures indicates that the optically bright regions are consistent with surface water ice whereas dark regions are consistent with a surface layer of complex organic material that likely overlies buried ice and provides thermal insulation impacts of comets or volatile rich asteroids could have provided both dark and bright deposits

major controls on sedimentation during the evolution of a continental basin pliocene pleistocene of the guadix basin betic cordillera southern spain abstract sequence stratigraphy based on climatic tectonic and base level parameters can be used to understand carbonate sedimentation in continental basins the uppermost continental fill of the guadix basin betic cordillera containing both siliciclastics and carbonates is investigated here in its central sector a thick succession of fluvio lacustrine sediments appear hosting several important pliocene and pleistocene macrovertebrate sites fonelas project the need to characterize the stratigraphic and sedimentologic context of these important paleontologic sites has lead to litho magneto and biostratigraphic studies these data together with the sedimentologic analysis of the pliocene and pleistocene siliciclastic and carbonate successions establish a sedimentary model for the fluvio lacustrine sedimentation of the two last stages of sedimentation in the guadix basin units v and vi unit v comprises mostly fluvial siliciclastic sediments with less abundant carbonate beds interpreted as floodplain lakes or ponds the latter unit vi is dominated by vertically stacked carbonate palustrine successions using two pre existent continental stratigraphic models the influence of climate tectonism and stratigraphic base level during the last 3 5 ma on the sedimentary evolution of the fluvio lacustrine system in the guadix basin especially the carbonate sedimentation patterns is outlined

structures and textures in triassic braided stream conglomerates bunter pebble beds in the sherwood sandstone group north staffordshire england in the northern parts of the needwood and stafford eccleshall basins england the pebble beds of the sherwood sandstone group contain thick successions of texturally mature fluvial pebble cobble conglomerates which are organized into either horizontal or cross stratified sets the horizontally lying sets generally coarser grained and more poorly sorted than the cross bedded sets are usually disorganized and either matrix or clast supported although thin lenses of well sorted occasionally openwork units interpreted as falling stage phenomena are often present the cross stratified conglomerates have foresets exhibiting remarkable textural organization with a coarse bimodal sometimes matrix supported part grading upwards or being abruptly overlain by a finer well sorted occasionally openwork part and finally capped by sandstone these rhythmic textural changes are attributed partly to an avalanche process at high stage and partly to falling stage conditions the most common types of vertical association are thick successions of horizontally bedded conglomerates up to 20 m and sequences of an upwards coarsening nature 2 12 m in which cross stratified sets are overlain by flat lying sets the environment of deposition of the gravels is interpreted as one in which water depths at high stage were greater than depths in most modern braided stream plains proglacial or alluvial fan but shallower than depths associated with the pleistocene catastrophic floods from which texturally mature giant gravel bars have been recorded recent braided streams with relatively confined channels and considerable bar channel relief are better analogues in particular medial or mid channel bars with a two tier structure subaqueous and partly emergent portions may explain the upward coarsening sequences in which horizontally lying conglomerates overlie cross stratified conglomerates the thicker sequences of horizontally stratified conglomerates represent proximal longitudinal bar deposits sheets of pebbly sandstone and argillaceous sandstone lying between the conglomerates and commonly occurring towards the top of the succession largely represent deposition from sandwaves and dunes finer interbedded argillaceous sandstones siltstones and mudstones are interpreted as overbank and waning flood deposits basin forming tectonism of increasing intensity probably caused the initial coarsening upwards of the lower part of the succession whilst more stable tectonic conditions and decreasing relief on the margins of the basins and in the areas of provenance in the midlands and the hercynides account for the upwards fining of the upper part of the succession

near surface temperatures on mercury and the moon and the stability of polar ice deposits abstract in order to assess the thermal stability of polar ice deposits we present model calculated temperatures of flat surfaces and surfaces within bowl shaped and flat floored polar impact craters on mercury and the moon our model includes appropriate insolation cycles realistic crater shapes multiple scattering of sunlight and infrared radiation and depth and temperature dependent regolith thermophysical properties unshaded water ice deposits on the surface of either body are rapidly lost to thermal sublimation a subsurface water ice deposit is stable within 2 latitude of the moon s poles meter thick water ice deposits require billions of years to sublime if located in the permanently shaded portions of flat floored craters within 10 latitude of the poles of mercury and 13 latitude of the poles of the moon results for craters associated with radar features on mercury are consistent with the presence of stable water ice deposits if a thin regolith layer thermally insulates deposits at lower latitudes and within smaller craters a regolith cover would also reduce losses from diffusion ion sputtering impact vaporization and h ly and is implied independently by the radar observations permanently shaded areas near the moon s poles are generally colder than those near mercury s poles but the moon s obliquity history its orbit through earth s magnetospheric tail and its radar opaque regolith may limit the volume and radar detectability of ice deposits there

a geologic model for lunar ice deposits at mining scales abstract water ice has been detected at the lunar poles but existing and near future orbital datasets do not have the capabilities to determine its horizontal and vertical distribution at meter to hundred meter scales relevant for mining operations additionally there has not yet been a coherent geologic model put forward for how ice deposits have formed and evolved that can be used to assist in planning prospecting campaigns or developing relevant hardware here we propose a system model for understanding these deposits at scales of meters to hectares the model considers sources of water ice capture at and below the surface and retention it focuses heavily on impact gardening as a modifying process that drives changes in how ice is distributed 3 dimensional stochastic impact simulations are then used to test the system model and explore how ice deposits might evolve over an area the size of a potential mining outpost the simulation results showed ice concentrations should eventually become fairly homogeneous at meter to hectare scales due to impact gardening and high concentrations are distributed randomly rather than clustered in earth like ore bodies we found the best ice deposits for extracting likely exist 10s of cm deep or more even in locations where ice is currently stable at the very surface terrestrial mining software was then used to create block models and grade tonnage curves that can inform future in situ resource utilization demonstration missions and future mining operations planning

illumination conditions of the lunar polar regions using lola topography abstract we use high resolution altimetry data obtained by the lunar orbiter laser altimeter instrument onboard the lunar reconnaissance orbiter to characterize present illumination conditions in the polar regions of the moon compared to previous studies both the spatial and temporal extent of the simulations are increased significantly as well as the coverage fill ratio of the topographic maps used thanks to the 28 hz firing rate of the five beam instrument we determine the horizon elevation in a number of directions based on 240 m resolution polar digital elevation models reaching down to 75 latitude the illumination of both polar regions extending to 80 can be calculated for any geometry from those horizon longitudinal profiles we validated our modeling with recent lunar reconnaissance orbiter wide angle camera images we assessed the extent of permanently shadowed regions psrs defined as areas that never receive direct solar illumination and obtained total areas generally larger than previous studies 12 866 and 16 055 km2 in the north and south respectively we extended our direct illumination model to account for singly scattered light and found that every psr does receive some amount of scattered light during the year we conducted simulations over long periods several 18 6 years lunar precession cycles with a high temporal resolution 6 h and identified the most illuminated locations in the vicinity of both poles because of the importance of those sites for exploration and engineering considerations we characterized their illumination more precisely over the near future every year a location near the shackleton crater rim in the south polar region is sunlit continuously for 240 days and its longest continuous period in total darkness is about 1 5 days for some locations small height gains 10 m can dramatically improve their average illumination and reduce the night duration rendering some of those particularly attractive energy wise as possible sites for near continuous sources of solar power

evidence for ultra cold traps and surface water ice in the lunar south polar crater amundsen abstract the northern floor and wall of amundsen crater near the lunar south pole is a permanently shaded region psr previous study of this area using data from the lunar orbiter laser altimeter lola diviner and lamp instruments aboard lunar reconnaissance orbiter lro shows a spatial correlation between brighter 1064 nm albedo annual maximum surface temperatures low enough to enable persistence of surface water ice we find features in far ir emissivity 50 400 m could be attributed to either or a combination of two effects i differential regolith emissive behavior between permanently shadowed temperature regimes and those of normally illuminated polar terrain perhaps related to presence of water frost as indicated in other studies or ii high degrees of anisothermality within observation fields of view caused by doubly shaded areas within the psr target that are colder than observed brightness temperatures the implications in both cases are compelling the far ir emissivity curve of lunar cold traps may provide a metric for the abundance of micro cold traps that are ultra cool i e shadowed also from secondary and higher order radiation absorption and re radiation or scattering by surrounding terrain or for emissive properties consistent with the presence of surface water ice

subsurface ice on mars with rough topography high latitude ground ice on mars discovered by the gamma ray spectrometer suite is thought to be thermally stable owing to the presence of vapor in the martian atmosphere however local slopes can alter surface and subsurface temperatures substantially and hence allow ground ice to persist at locations where it would otherwise be unstable global statistics of the topography of mars are computed processed and extrapolated to derive a description of surface roughness on spatial scales to which ground ice should be sensitive this slope distribution is convolved with a new thermal model for the dependence of subsurface ice on slope to produce a prediction of the global ice distribution that includes the effect of topographic roughness in the highest latitudes slopes reduce the amount of buried ice while in lower latitudes the ice fraction increases widening the geographic boundary of the ice table at the high latitudes where ice is stable beneath horizontal ground the estimated reduction of ice is small compared to the existing ice volume areas in the midlatitudes with high surface roughness that have previously been predicted to be ice free are predicted to contain quantities of ice that may be detectable at present and accessible in the future slopes cause ground ice to be stable to latitudes of about 25 degrees in both hemispheres including for example areas within the northern olympus mons aureole deposits hecates tholus and hellas basin ice is unstable at equatorial latitudes even when accounting for surface slopes

subsurface migration of h2o at lunar cold traps 1 permanently shaded areas near the poles of the moon and mercury may harbor water ice we develop a physical model for migration of water molecules in the regolith and discover two pathways that can lead to accumulation of h2o in the subsurface a small fraction of water molecules delivered either continuously or abruptly to permanently cold areas diffuses into the regolith and can remain there longer than on the surface higher temperatures lead to deeper burial at constant temperature this diffusive migration produces less than one molecular layer of volatile h2o on grains because it is driven by differences in surface concentrations the water is therefore expected to be in adsorbed form and the amount stored in this fashion could be at most a few hundred ppm of h2o a second pathway is pumping by diurnal temperature oscillations from a transient ice cover that may have formed during a large comet impact it can lead to high ground ice densities but the ground ice layer lasts not long beyond the disappearance of the ice cover both types of subsurface charging mechanism work best for temperatures typical of permanently shaded areas with sunlit surfaces in their field of view

images of surface volatiles in mercury s polar craters acquired by the messenger spacecraft images acquired by nasa s messenger spacecraft have revealed the morphology of frozen volatiles in mercury s permanently shadowed polar craters and provide insight into the mode of emplacement and evolution of the polar deposits the images show extensive spatially continuous regions with distinctive reflectance properties a site within prokofiev crater identified as containing widespread surface water ice exhibits a cratered texture that resembles the neighboring sunlit surface except for its uniformly higher reflectance indicating that the surficial ice was emplaced after formation of the underlying craters in areas where water ice is inferred to be present but covered by a thin layer of dark organic rich volatile material regions with uniformly lower reflectance extend to the edges of the shadowed areas and terminate with sharp boundaries the sharp boundaries indicate that the volatile deposits at mercury s poles are geologically young relative to the time scale for lateral mixing by impacts and either are restored at the surface through an ongoing process or were delivered to the planet recently

karst subsidence as a control on the accumulation and preservation of aeolian deposits a pleistocene example from a proglacial outwash setting ebro basin spain meltwater flows emanating from the pyrenees during the pleistocene constructed a braided outwash plain in the ebro basin and led to the karstification of the neogene gypsum bedrock synsedimentary evaporite dissolution locally increased subsidence rates and generated dolines and collapses that enabled the accumulation and preservation of outwash gravels and associated windblown deposits that were protected from erosion by later meltwater flows in these localized depocentres maximum rates of wind deceleration resulted from airflow expansion enabling the accumulation of cross stratified sets of aeolian strata climbing at steep angles and thereby preserving up to 5 m thick sets the outwash plain was characterized by longitudinal and transverse fluvial gravel bars channels and windblown facies organized into aeolian sand sheets transverse and complex aeolian dunes and loess accumulations flat lying aeolian deposits merge laterally to partly deformed aeolian deposits encased in dolines and collapses synsedimentary evaporite dissolution caused gravels and aeolian sand deposits to subside such that formerly near horizontal strata became inclined and generated multiple internal angular unconformities during episodes when the wind was undersaturated with respect to its potential sand transporting capacity deflation occurred over the outwash plain and coarse grained lags with ventifacts developed subsequent high energy flows episodically reached the aeolian dune field leading to dune destruction and the generation of hyperconcentrated flow deposits composed in part of reworked aeolian sands lacustrine deposits in the distal part of the outwash plain preserve rhythmically laminated lutites and associated gilbert type gravel deltas which developed when fluvial streams reached proglacial lakes this study documents the first evidence of an extensive pleistocene proglacial aeolian dune field located in the ebro basin 41 50 n south of what has hitherto been considered to be the southern boundary of pleistocene aeolian deposits in europe a non conventional mechanism evaporite karst related subsidence for the preservation of aeolian sands in the stratigraphic record is proposed

quantitative geomorphology of the mars eberswalde delta the eberswalde delta is composed of six separate depositional lobes that have prograded some 17 km from their apex crosscutting distributary relationships and compensated depositional lobes are clearly visible in images acquired by the mars global surveyor mars orbiter camera here several lobe systems have been examined for sinuosity radius of channel curvature meander bend width and channel width parameters channel sinuosities of between 1 2 and 1 8 defi ne low to moderate sinuosity systems typical of the type transporting bedload or mixed grain size loads channel systems increase in sinuosity as they get older however some of the younger systems show specifi c reaches of increased sinuosity these localized changes may be due to either abutment against resistant beds of older lobes or rise in base level at the channel system terminus if the former such an effect of older deposits on the morphology of the channels suggests that these older lobes were fairly well indurated prior to the deposition of the youngest progradational lobes eighty six percent of distributaries in the mars eberswalde delta are 100 240 m wide comparatively 62 and 44 of distributaries in the atchafalaya and wax lake deltas of louisiana respectively are of similar size small distributaries may indicate lower average and shorter duration fl ows or coarser sediment in mars distributaries than those typical of the gulf coast systems the volume of the material in the mars deposit suggests long periods of sediment deposition sinuosity indexes meander bend migration and ridge and swale point bar topography suggest periods of stable discharge on the delta surface

differential features of alluvial fans controlled by tectonic or eustatic accommodation space examples from the betic cordillera spain abstract the creation of accommodation space in subaerial sedimentary environments is closely linked to uplift the source area along basin margin faults or to a rise in base level depending amongst others on the relative importance of these two factors the margins of terrestrial sedimentary basins where alluvial fans develop produce aggradational progradational or retrogradational stratigraphic architecture we studied a total of 43 quaternary alluvial fans in the granada and bajo segura basins betic cordillera spain the analysis of their stratigraphic architecture and sedimentary facies has revealed the existence of three groups characterised by distinct stratal stacking patterns which is the result of differences in eustasy and tectonics the qualitative and quantitative analysis of these alluvial fans and their drainage basins has allowed us to define certain characteristic geomorphological patterns related in each case to the main mechanism operative in the creation of accommodation space these patterns are described as follows 1 alluvial aggradation is the main result of high tectonic subsidence with the development of quite open but small fans with a constant steep slope lacking incised channels and headward eroding gullies 2 in contrast when the principal mechanism in creating accommodation space is low tectonic subsidence progradation occurs and the fans are narrower and larger moreover the slopes of such fans are less steep in relation to the drainage area than in the above case being constant or even concave in longitudinal profile they also have short deep incised channels culminating downfan in a depositional lobe in inactive zones long deep headward eroding gullies develop 3 areas of extremely low tectonic subsidence and base level rise produce very open fans in the sedimentary basin although with a pronounced mountain embayment which gives them a characteristic mushroom shape in plan view in the latter case retrogradation is the typical stratigraphic stacking pattern and the fans are quite extensive with respect to their drainage areas usually showing a segmented longitudinal profile with a low gradient the feeder channels do not surpass stream order 3 and various extremely long and shallow incised channels can appear 4 contrary to the case of fans developing under a regime of subsidence when the accommodation is due to base level rise the fan slopes bear no relation to the extent of the catchment basins in such a case the overall fan slope is strongly influenced by the extent of the mountain embayment because it determines the distributions of debris and sheet flows over the alluvial surface

global surface slopes and roughness of the moon from the lunar orbiter laser altimeter 1 the acquisition of new global elevation data from the lunar orbiter laser altimeter carried on the lunar reconnaissance orbiter permits quantification of the surface roughness properties of the moon at unprecedented scales and resolution we map lunar surface roughness using a range of parameters median absolute slope both directional along track and bidirectional in two dimensions median differential slope and hurst exponent over baselines ranging from 17 m to 2 7 km we find that the lunar highlands and the mare plains show vastly different roughness properties with subtler variations within mare and highlands most of the surface exhibits fractal like behavior with a single or two different hurst exponents over the given baseline range when a transition exists it typically occurs near the 1 km baseline indicating a significant characteristic spatial scale for competing surface processes the hurst exponent is high within the lunar highlands with a median value of 0 95 and lower in the maria with a median value of 0 76 the median differential slope is a powerful tool for discriminating between roughness units and is useful in characterizing among other things the ejecta surrounding large basins particularly orientale as well as the ray systems surrounding young copernican age craters in addition it allows a quantitative exploration on mare surfaces of the evolution of surface roughness with age

late pleistocene and holocene mid latitude palaeoclimatic and palaeoenvironmental reconstruction an approach based on the isotopic record from a travertine formation in the guadix baza basin spain a comprehensive palaeoenvironmental reconstruction of the last 219 ka has been carried out by determining the isotopic signatures 18 o and 13 c in 766 samples of a thermogene travertine formation in the guadix baza tertiary basin granada se spain this travertine formation was dated from 220 to 5 ka by means of the alpha spectrometry technique initially the study of the 18 o values of the travertine formation was carried out because they are excellent indicators of the overall palaeoclimatic condition of a particular site likewise the evolution of 13 c values which can be directly related to the biomass development of the site has also been studied finally an integrated study of both isotopic records has been performed identifying a total of 12 climatic periods based on their palaeoclimatic and palaeoenvironmental conditions these periods are grouped into four climatic scenarios scenario a characterized by warm and dry periods scenario b characterized by cold and humid periods scenario c constituted by warm and humid periods and scenario d which is characterized by cold and dry periods palaeoclimatic scenarios a and b mainly characterized the palaeoclimatic evolution of the site while in northern europe the palaeoclimatic evolution is mainly characterized by scenarios c and d therefore it is suggested that the palaeoenvironmental evolution at lower latitudes on the iberian peninsula is the opposite of that identified in northern europe however the main climatic events identified at higher latitudes are also reflected in the studied area