hydrogeochemistry of dal lake and the potential for present future management by using facies ionic ratios and statistical analysis this paper presents the inventory study on the dal lake the second largest fresh water lake in kashmir valley india a total of 336 water samples were monthly collected to assess the present scenario of weathering and anthropogenic impact on water for hydrological year 2012 2013 the results showed a significant spatio temporal monthly and basinal variability in the concentration of the physical and chemical characteristics major ions of the lake water the lake water is alkaline in nature ph 7 1 8 7 characterized by medium total dissolved solids of 80 8 230 7 mg l 1 and electrical conductivity of 126 3 384 6 s cm 1 the order of major cations and anions is ca2 mg2 na k and hco3 so42 cl no3 respectively the geochemical processes suggested that the lake water composition is mostly influenced by the lithology of the catchment ca mg hco3 was found to be the dominant hydrochemical facies followed by mixed type of water throughout the hydrological year from sub basin point of view all the four basins show ca mg hco3 type water but hazratbal and nigeen basins also show shift towards so4 and cl type of water reflecting the anthropogenic inputs in these two basins basin wise the average concentration of ca2 mg2 hco3 cl and no3 were highest in nigeen basin due to high resistance time of water within the basin and na k and so42 in hazratbal basin from the silicate weathering and sewage plant sources the gagribal basin showed lowest values of ca2 na k hco3 and cl whereas boddal and hazratbal basin showed lowest values of so42 no3 and mg2 respectively on monthly basis ca2 na k and hco3 were highest in april mg2 and no3 in january cl in december and so42 in september lower value of ca2 and cl were observed in july mg2 in april and hco3 and k in august the study suggested that the predominant processes influencing water chemistry were congruent carbonate dissolution 61 9 and incongruent silicate weathering 12 7 and cation exchange of na in rocks for ca2 and mg2 10 the high major ion concentrations indicated long water rock interactions and long residence time of water in the lake the higher concentrations so42 no3 and cl reflect anthropogenic inputs from the immediate catchment

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

geochemical characteristics of water and sediment from the dal lake kashmir himalaya constraints on weathering and anthropogenic activity two hundred and forty water samples in four seasons and seventeen sediment samples have been analyzed to monitor the natural and anthropogenic influences on the water and sediment chemistry of the dal lake kashmir himalaya the scatter diagrams ca mg total cations tz ca mg hco3 ca mg hco3 so4 na k tz ca mg na k and the geological map of the study area suggest predominance of carbonate and silicate weathering lower ph and high total dissolved solids electrical conductivity and text no text 3 values in the gagribal basin and in some patches of other basins reflect anthropogenic inputs in the form of sewage from surrounding population houseboats hotels etc the dal lake is characterized by high chemical index of alteration cia 87 95 reflecting extreme weathering of the catchment area relative to the average carbonates the lakebed sediments are enriched in al ti zn cu and co and depleted in ni and mn compared to the post archean shale the sediments have higher al zn and cu contents and lower ni and co there are distinct positive anomalies of al mn zn and cu and negative anomalies of ni and pb with respect to the upper continental crust geoaccumulation index igeo and the us environmental protection agency sediment quality standards indicate that the gagribal basin and some patches of the nagin basin are polluted with respect to zn cu and pb these data suggest that the dal lake is characterized by differential natural and anthropogenic influences

young late amazonian near surface ground ice features near the equator athabasca valles mars abstract a suite of four feature types in a 20 km 2 area near 10 n 204 w in athabasca valles is interpreted to have resulted from near surface ground ice these features include mounds conical forms with rimmed summit depressions flatter irregularly shaped forms with raised rims and polygonal terrain based on morphology size and analogy to terrestrial ground ice forms these athabascan features are interpreted as pingos collapsing pingos pingo scars and thermal contraction polygons respectively thermal infrared mapping spectrometer themis data and geological features in the area are consistent with a sedimentary substrate underlying these features these observations lead us to favor a ground ice interpretation although we do not rule out volcanic and especially glaciofluvial hypotheses the hypothesized ground ice that formed the mounds and rimmed features may have been emplaced via the deposition of saturated sediment during flooding an alternative scenario invokes magmatically cycled groundwater the ground ice implicit in the hypothesized thermal contraction polygons may have derived either from this flooding ground water or from atmospheric water vapor the lack of obvious flood modification of the mounds and rimmed features indicates that they formed after the most recent flood inundated the area analogy with terrestrial pingos suggests that ground ice may be still extant within the positive relief mounds as the water that flooded down athabasca valles emerged via a volcanotectonic fissure from a deep aquifer any extant pingo ice may contain evidence of a deep subsurface biosphere

evidence for basaltic volcanism on the moon within the past 100 million years the majority of basaltic volcanism on the moon occurred more than 3 billion years ago small mounded formations on the lunar nearside may be products of basaltic eruptions less than 100 million years ago suggesting a long decline of magmatic activity

chronostratigraphy of loess deposits in northeast iran little information is available on the paleoclimate evolution of northeast iran relating to global cold and warm stages the loess paleosol sequences from southern mashhad and kalat e naderi areas were studied to determine the landscape evolution and to set up the first chronological framework for the pleistocene deposits in northeast iran the loess deposits in these areas are less thick up to 12 m and have a more patchy distribution than in the caspian lowland of northern iran infrared stimulated luminescence irsl dating of loess or loess derivatives from the robat e khakestari tappeh salam and deh gheybi sections a and b from southern mashhad as well as kalat e naderi sections a and b in kalat e naderi area provides a more reliable chronological framework for climate and environmental changes taken place over for the time period including the penultimate and last interglacial glacial cycles the robat e khakestari section the kalat e naderi sections a and b and to some extent the tappeh salam section include loess paleosol sequences which are chronologically in excellent agreement with the loess record of the caspian lowland in northern iran the deh gheybi sections a and b include loess like sediments and fluvial deposits that make their interpretation difficult loess accumulated during mis 2 at the robat e khakestari section and at the kalat e naderi sections a and b suggesting a more windy and arid last glacial maximum lgm in northeast iran paleosols correlating most likely with mis 5 were covered by fluvial sediments at the kalat e naderi section a the absence of loess deposits correlating to mis 3 and mis 4 at the robat e khakestari section is very likely to have been caused by fluvial processes and water erosion

evidence from the mars express high resolution stereo camera for a frozen sea close to mars equator it is thought that the cerberus fossae fissures on mars were the source of both lava and water floods two to ten million years ago evidence for the resulting lava plains has been identified in eastern elysium but seas and lakes from these fissures and previous water flooding events were presumed to have evaporated and sublimed away here we present high resolution stereo camera images from the european space agency mars express spacecraft that indicate that such lakes may still exist we infer that the evidence is consistent with a frozen body of water with surface pack ice around 5 degrees north latitude and 150 degrees east longitude in southern elysium the frozen lake measures about 800 x 900 km in lateral extent and may be up to 45 metres deep similar in size and depth to the north sea from crater counts we determined its age to be 5 2 million years old if our interpretation is confirmed this is a place that might preserve evidence of primitive life if it has ever developed on mars

the current martian cratering rate abstract the discovery of 248 dated impact sites known to have formed within the last few decades allows us to refine the current cratering rate and slope of the production function at mars we use a subset of 44 of these new craters that were imaged before and after impact by mars reconnaissance orbiter s context camera a thoroughly searched data set that minimizes biases from variable image resolutions we find the current impact rate is 1 65 10 6 craters with an effective diameter 3 9 m km2 yr with a differential slope power law exponent of 2 45 0 36 this results in model ages that are factors of three to five below the hartmann hartmann w k 2005 icarus 174 294 320 and neukum et al neukum g ivanov b a hartmann w k 2001 space sci rev 96 55 86 ivanov ivanov b a 2001 space sci rev 96 87 104 model production functions where they overlap in diameter the best fit production function we measure has a shallower slope than model functions at these sizes but model function slopes are within the statistical errors more than half of the impacts in this size range form clusters which is another reason to use caution when estimating surface ages using craters smaller than 50 m in diameter

constraints on ripple migration at meridiani planum from opportunity and hirise observations of fresh craters 1 observations of fresh impact craters by the opportunity rover and in high resolution orbital images constrain the latest phase of granule ripple migration at meridiani planum to have occurred between 50 ka and 200 ka opportunity explored the fresh resolution crater cluster and concepcion crater that are superposed on and thus younger than the ripples these fresh craters have small dark pebbles scattered across their surfaces which are most likely fragments of the impactor suggesting that the dark pebbles and cobbles observed by opportunity at meridiani planum are a lag of impactor derived material either meteoritic or secondary impactors from elsewhere on mars two larger fresh rayed craters in meridiani planum bracket ripple migration secondaries from ada crater are clearly superposed on and secondaries from an unnamed 0 84 km diameter crater have been modified and overprinted by the ripples three methods were used to estimate the age of these craters and thus when the latest phase of ripple migration occurred the inactivity of the ripples over the past 50 ka at meridiani is also consistent with other evidence for the stability of the ripples the lack of observed eolian bed forms in craters that formed in the past 20 years and little evidence for much dune motion in the past 30 yr on mars observations of crater morphology and their interaction with the ripples allow the development of a general time scale for craters in meridiani planum over the past million years

the lassell massif a silicic lunar volcano abstract lunar surface volcanic processes are dominated by mare producing basaltic extrusions however spectral anomalies landform morphology and granitic or rhyolitic components found in the apollo sample suites indicate limited occurrences of non mare geochemically evolved si enriched volcanic deposits recent thermal infrared spectroscopy high resolution imagery and topographic data from the lunar reconnaissance orbiter lro show that most of the historic red spots and other less well known locations on the moon are indeed silica rich relative to basalt here we present a geologic investigation of the lassell massif 14 65 s 350 96 e near the center of alphonsus a basin in mare nubium where high silica thermal emission signals correspond with morphological indications of viscous possibly also explosive extrusion and small scale low reflectance deposits occur in a variety of stratigraphic relationships multiple layers with stair step lobate forms suggest different eruption events or pulsing within a single eruption absolute model ages derived from crater size frequency distributions csfds indicate that the northern parts of the massif were emplaced at 4 ga before the surrounding mare however csfds also indicate the possibility of more recent resurfacing events the complex resurfacing history might be explained by either continuous resurfacing due to mass wasting and or the emplacement of pyroclastics relatively low reflectance deposits are visible at meter scale resolutions below detection limits for compositional analysis at multiple locations across the massif suggestive of pyroclastic activity a quenched flow surface or late stage mafic materials compositional evidence from 7 band uv vis spectral data at the kilometer scale and morphologic evidence for possible caldera collapse and or explosive venting support the interpretation of a complex volcanic history for the lassell massif

hydrogeochemical characterization and groundwater quality assessment in the intensive agricultural zone of the upper cheliff plain algeria the alluvial aquifer of upper cheliff northern algeria is known for its intensive agricultural activities which is based especially on groundwater exploitation this aquifer is now facing a dual problem of quantity and quality with a decrease in the groundwater levels and an increase in mineralization twenty monitoring samples were collected and analyzed for major ion during the dry season 2014 in the present study we try to characterize the hydrogeochemical processes and to assess the impact of natural and anthropogenic conditions on groundwater mineralization the analytical results of the dry season 2014 show a groundwater quality slightly alkaline ph 7 and indicate that the majority of samples have a values exceeding the limits of potability fixed by who in 2008 due to the various sources of anthropogenic pollution the piper diagram shows the dominance of groundwater types ca cl the mixed facies cl so4 ca mg and ca hco3 the mineralization process in this aquifer is mainly controlled by the lithology of the aquifer exchange water rock and weathering of calcareous crust dissolution in the unsaturated zone by anthropogenic factors discharges of untreated urban sewage intensive use of fertilizers in agriculture and the use of domestic septic tanks by rural inhabitants and also by geoclimatic conditions semiarid climate suitability of groundwater shows more than 80 of samples have very poor quality for drinking and more than 20 of samples indicate a quality unsuitable for irrigation

emplacement of the youngest flood lava on mars a short turbulent story abstract recently acquired data from the high resolution imaging science experiment hirise context ctx imager and compact reconnaissance imaging spectrometer for mars crism onboard the mars reconnaissance orbiter mro spacecraft were used to investigate the emplacement of the youngest flood lava flow on mars careful mapping finds that the athabasca valles flood lava is the product of a single eruption and it covers 250 000 km 2 of western elysium planitia with an estimated 5000 7500 km 3 of mafic or ultramafic lava calculations utilizing topographic data enhanced with mro observations to refine the dimensions of the channel system show that this flood lava was emplaced turbulently over a period of only a few to several weeks this is the first well documented example of a turbulently emplaced flood lava anywhere in the solar system however mro data suggest that this same process may have operated in a number of martian channel systems the magnitude and dynamics of these lava floods are similar to the aqueous floods that are generally believed to have eroded the channels raising the intriguing possibility that mechanical erosion by lava could have played a role in their incision

geomorphology and late holocene morphogenesis of tchinguiz tepe hill old termez uzbekistan central asia tchinguiz tepe hill is the southernmost outcrop interrupted at the shores of the amu darya of the cenozoic sediments that form the baysuntau kugitangtau alignment the initiation points of the recent morphogenesis are the slopes and a pediment controlled structurally by the unequally weathered substrate the hill is covered by sediments of varying thickness on the south side which is exposed to dominant winds from the se and was occupied by humans at least during kushan times 1st and 2nd centuries ad its form is derived from two systems of natural processes slope and aeolian and an anthropic one which have operated under arid to semiarid conditions these processes have mobilized sands from the weathered substrate and from the afghan dunes and pebbles and gravels from early kushan time constructions such as the fortress of the tchingiz tepe hill slope wash processes have contributed materials which have evolved as slope aeolian sediment in the mantled pediment part of the aeolian sand has been re exported together with primary autochthonous sand outside the hill towards the north thus in tchinguiz tepe the current morphogenesis has slowed down considerably and is currently in dynamic equilibrium with a slow increase in sediments the carbonate crusts which are not very well developed have formed a complex host sediment anthropic morphogenetic action has modified the natural shape of the hill from the earliest times of occupation to the present day and has generated materials that are now incorporated in the slope wash and govern the current topography and the distribution of sediments from the wall of the fortress and other buildings

role of material properties in the cratering record of young platy ridged lava on mars 1 platy ridged surfaces in the elysium planitia region of mars exhibit different crater densities on rafted plates and polygonally patterned areas between them rather than being indicative of different ages these differences provide insight into the variable strength of different types of lava surface the sizes of small craters and the resulting size frequency distribution sfd depend on the material strength of target surfaces brecciated lava surfaces are likely to have higher crater densities than coherent lava

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

the use of hydrogeochemical analyses and multivariate statistics for the characterization of groundwater resources in a complex aquifer system a case study in amyros river basin thessaly central greece the present study investigates the hydrogeochemical regime of a complex aquifer system in a highly cultivated area of thessaly central greece to do so totally forty 40 groundwater samples were collected for three aquifer units with diverse geological and hydrogeological attributes and analyzed for 77 parameters data processing was accomplished with the joint use of classic hydrogeochemical techniques including major ion molar ratios and graphical interpretation as well as multivariate statistical methods including r mode factor fa and hierarchical cluster analysis hca results showed that major ion hydrogeochemistry is characterized by the prevalence of calcium median 81 mg l and bicarbonates median 308 mg l in the following descending order of concentrations for cations ca2 mg2 na k and anions hco3 no3 so42 cl respectively nitrate values are elevated median 23 mg l especially in the porous quaternary aquifer indicating the ongoing agricultural impact from the excessive use of nitrogen fertilizers and manure the results of multivariate statistics highlighted four factors that chiefly control 81 4 of overall hydrogeochemistry related with both geogenic and anthropogenic impacts the geogenic impact is mainly attributed to the geological substrate and secondarily to the ongoing geochemical redox conditions which in turn enrich or deplete groundwater solution with different ions anthropogenic impact is mainly related with the extensive agricultural practices which favor nitrate enrichment and salinization due to irrigation water return flow

the flood lavas of kasei valles mars abstract both the northern and southern arms of kasei valles are occupied by platy ridged flood lavas we have mapped these flows and examined their morphology to better understand their emplacement the lavas were emplaced as high flux turbulent flows exceeding 106 m3 s 1 lava in southern kasei valles can be traced back up onto the tharsis rise which is also the likely source of lavas in the northern arm these eruptions were similar to but somewhat smaller than the athabasca valles flood lava in elysium planitia with estimated volumes of 1200 km3 here and 5000 km3 in athabasca valles the flood lavas in both kasei and athabasca valles have evidence for distal inflation as well as widespread drainage or volume loss in medial areas this may be an important characteristic of many large recent martian eruptions despite their great size and flux the kasei valles flood lavas are only a late modification to the valley system capable of only modest local erosion the more vigorous athabasca valles lava may have been capable of somewhat more erosion in its smaller valley system

recharge mechanisms and geochemical processes in a semi arid sedimentary basin eastern cape south africa abstract stable isotope 18 o and 2 h and geochemical signatures are used to gain some insight into recharge processes and groundwater salinization mechanisms in a semi arid rangeland catchment the 665 km 2 catchment is underlain by fractured lower beaufort sandstones and mudstones and is intruded by several dolerite dykes chloride and isotopic relationships suggest that chloride ions in ground water are of meteoric origin the hypothesized recharge and salinization mechanism is that large storm events periodically dissolve accumulated surficial meteoric salts and after a period of evaporative enrichment at or near the soil surface leach them into the ground water geochemical variations imply that spatial differences exist in recharge volumes in evaporative enrichment or in the extent of leaching of surficial salts meteoric sodium chloride contributes greater than 90 of the dissolved sodium except at low salinities where cation exchange processes yield additional sodium inputs in exchange for dissolved calcium and magnesium at high salinities this process reverses and sodium is adsorbed releasing calcium and magnesium this process accounts for up to 40 of the dissolved calcium and magnesium contributions from geochemical weathering are relatively uniform in spite of highly variable salinities which implies that residence times are also relatively uniform

geologic map of the northern hemisphere of vesta based on dawn framing camera fc images abstract the dawn framing camera fc has imaged the northern hemisphere of the asteroid 4 vesta at high spatial resolution and coverage this study represents the first investigation of the overall geology of the northern hemisphere 22 90 n quadrangles av 1 2 3 4 and 5 using these unique dawn mission observations we have compiled a morphologic map and performed crater size frequency distribution csfd measurements to date the geologic units the hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to 200 km in diameter the most widespread unit is a plateau cratered highland unit similar to although of lower elevation than the equatorial vestalia terra plateau large scale troughs and ridges have regionally affected the surface between 180 e and 270 e these tectonic features are well developed and related to the south pole veneneia impact saturnalia fossae trough unit elsewhere on the hemisphere they are rare and subdued saturnalia fossae cratered unit in these pre rheasilvia units we observed an unexpectedly high frequency of impact craters up to 10 km in diameter whose formation could in part be related to the rheasilvia basin forming event the rheasilvia impact has potentially affected the northern hemisphere also with s n small scale lineations but without covering it with an ejecta blanket post rheasilvia impact craters are small

athabasca valles mars a lava draped channel system athabasca valles is a young outflow channel system on mars that may have been carved by catastrophic water floods however images acquired by the high resolution imaging science experiment camera onboard the mars reconnaissance orbiter spacecraft reveal that athabasca valles is now entirely draped by a thin layer of solidified lava the remnant of a once swollen river of molten rock the lava erupted from a fissure inundated the channels and drained downstream in geologically recent times purported ice features in athabasca valles and its distal basin cerberus palus are actually composed of this lava similar volcanic processes may have operated in other ostensibly fluvial channels which could explain in part why the landers sent to investigate sites of ancient flooding on mars have predominantly found lava at the surface instead

early pleistocene climate cycles in continental deposits of the lesser caucasus of armenia inferred from palynology magnetostratigraphy and 40ar 39ar dating plio pleistocene diatomitic sequences in the shamb paleo lake south armenia lesser caucasus offer a rare opportunity to give new insights on the paleo climate of western asia we present an integrated palynological 40ar 39ar geochronologic and magnetostratigraphic study for the most complete section in the sedimentary deposits of the shamb paleo lake 40ar 39ar dating of two volcaniclastic layers provided ages of 1 24 0 03 and 1 16 0 02 ma 2 magnetostratigraphic data show that the entire shamb section is of reversed polarity which combined with 40ar 39ar dating suggests that the entire section correlates with part of the matuyama period 1 785 1 070 ma pollen assemblages and macroremains diversity clearly show an alternation of glacial and interglacial phases age calibrations and accumulation rate extrapolation allow a direct correlation of climate changes with the global isotopic curve and show that the shamb section probably ranges from approximately 1 300 to 1 080 ma marine isotopic stages 40 to 31 the vegetation of the lesser caucasus developed in a mosaic pattern in a pleistocene continental mostly arid climate comparable to the present day climate the observed vegetation changes record a dominant climate response to the obliquity orbital parameter but the influence of precession could not be established from the shamb data pollen and macroflora both indicate that glacial periods were cold and dry and that interglacials were warm with local humidity the early pleistocene climatic model for western asia is thus similar to the climatic model for the mediterranean area

dating martian climate change abstract geological evidence indicates that low latitude polygonally patterned grounds on mars generally thought to be the product of flood volcanism are periglacial in nature and record a complex signal of changing climate by studying the martian surface stratigraphically in terms of the geometrical relations between surface landforms and the substrate rather than genetically by form analogy with earth we have identified dynamic surfaces across one fifth of martian longitude new stratigraphical observations in the elysium amazonis plains have revealed a progressive surface polygonisation that is destructive of impact craters across the region this activity is comparable to the climatically driven degradation of periglacial landscapes on earth but because it affects impact craters the martian chronometer it can be dated here we show that it is possible to directly date this activity based on the fraction of impact craters affected by polygon formation nearly 100 of craters of all diameters are superposed by polygonal sculpture considering the few 100 ma age of the substrate this suggests that the process of polygon formation was active within the last few million years surface polygonisation in this region often considered to be one of the signs of young plains forming volcanism on mars is instead shown to postdate the majority of impact craters seen we therefore conclude that it is post depositional in origin and an artefact of thermal cycling of near surface ground ice stratigraphically controlled crater counts present the first way of dating climate change on a planet other than earth a record that may tell us something about climate change on our own planet parallel climate change on these two worlds an ice age mars coincident with earth s glacial quaternary period might suggest a coupled system linking both we have previously been unable to generalise about the causes of long term climate change based on a single terrestrial example with the beginnings of a chronology for climate change on our nearest planetary neighbour we can

sounding the subsurface of athabasca valles using marsis radar data exploring the volcanic and fluvial hypotheses for the origin of the rafted plate terrain 1 to test the volcanic and fluvial hypotheses for the origin of the rafted plate terrain observed in the vicinity of athabasca valles 5 n 150 e central elysium planitia we investigated the subsurface radar echo from the mars advanced radar for subsurface and ionosphere sounding marsis 5 mhz band data over this area the backscattered signal losses were compared to finite difference time domain fdtd simulations of those arising from three hypothetical geoelectrical subsurface models which differed in their assumed composition percentage basalt versus ice and assumed mode of origin fluvial discharge frozen sea mudflow and low viscosity lavas the dielectric values used in these models are derived from laboratory measurements of mars analog materials under mars like conditions fdtd simulations suggest that if the near surface environment is ice rich it will result in an average loss rate of 0 053 db m for massive ice having less than 1 of suspended particulates and 0 065 db m for a mudflow consisting of a 50 50 mixture of ice and basaltic dust whereas the losses associated with a lava flow model increase to 0 19 db m in comparison the actual signal losses experienced by marsis within this region were on the order of 0 18 db m within the first 160 m beneath the surface this suggests that propagation characteristics of athabasca s near subsurface are more consistent with a volcanic rather than a fluvial or mudflow origin of the rafted plate terrain although limitations on radar sounding depth in this region cannot rule out the possibility of more deeply buried massive ice deposits

a crater and its ejecta an interpretation of deep impact we apply recently updated scaling laws for impact cratering and ejecta to interpret observations of the deep impact event an important question is whether the cratering event was gravity or strength dominated the answer gives important clues about the properties of the surface material of tempel 1 gravity scaling was assumed in pre event calculations and has been asserted in initial studies of the mission results because the gravity field of tempel 1 is extremely weak a gravity dominated event necessarily implies a surface with essentially zero strength the conclusion of gravity scaling was based mainly on the interpretation that the impact ejecta plume remained attached to the comet during its evolution we address that feature here and conclude that even strength dominated craters would result in a plume that appeared to remain attached to the surface we then calculate the plume characteristics from scaling laws for a variety of material types and for gravity and strength dominated cases we find that no model of cratering alone can match the reported observation of plume mass and brightness history instead comet like acceleration mechanisms such as expanding vapor clouds are required to move the ejected mass to the far field in a few hour time frame with such mechanisms and to within the large uncertainties either gravity or strength craters can provide the levels of estimated observed mass thus the observations are unlikely to answer the questions about the mechanical nature of the tempel 1 surface

present day impact cratering rate and contemporary gully activity on mars the mars global surveyor mars orbiter camera has acquired data that establish the present day impact cratering rate and document new deposits formed by downslope movement of material in mid latitude gullies on mars twenty impacts created craters 2 to 150 meters in diameter within an area of 21 5 106 square kilometers between may 1999 and march 2006 the values predicted by models that scale the lunar cratering rate to mars are close to the observed rate implying that surfaces devoid of craters are truly young and that as yet unrecognized processes of denudation must be operating the new gully deposits formed since august 1999 are light toned and exhibit attributes expected from emplacement aided by a fluid with the properties of liquid water relatively long extended digitate distal and marginal branches diversion around obstacles and low relief the observations suggest that liquid water flowed on the surface of mars during the past decade

martian cratering 8 isochron refinement and the chronology of mars abstract this paper reviews and refines the technique of dating martian surfaces by using impact crater isochrons defined as size distributions of impact craters on undisturbed martian surfaces of specified ages in the 1970s this system identified not only abundant ancient martian volcanic surfaces but also extensive lava plains with ages of a few 108 y old this dating was initially controversial but confirmed in the 1980s and 90s by martian meteorites the present update utilizes updated estimates of the mars moon cratering ratio the most important calibration factor improves treatment of gravity and impact velocity scaling effects combines aspects of the crater size distribution data from earlier work by both neukum and hartmann and for the first time applies a correction for loss of small meteoroids in the martian atmosphere from popova et al 2003 meteorit planet sci 38 905 925 the updated isochrons are not radically different from the previous 2002 iteration but fit observed data better and give somewhat older model ages for features dated from small craters diameter d 100 m crater counts from young lava flows in various areas give good fits to the new isochrons over as much as 3 orders of magnitude in d confirming the general isochron shape and giving crater retention ages in the range of some 106 to some 108 y interpreted as lava flow ages more complex older units are also discussed uncertainties are greatest if only small craters d 100 m are used suggestions by other workers of gross uncertainties due to local secondary craters and deposition exhumation are discussed they do not refute our conclusions of significant volcanic fluvial and other geologic activity in the last few percent of martian geologic time or the importance of cratering as a tool for studying processes such as exhumation indeed crater count data suggest certain very recent episodes of deposition exhumation and ice flow possibly associated with obliquity cycles of 10 7 y timescale evidence from ancient surfaces suggests higher rates of volcanism fluvial activity glaciation and other processes in noachian hesperian time than in amazonian time

glacial interglacial cycles in arid regions of northern eurasia abstract considering evolution of arid environments in northern eurasia through the glaciation interglacial cycle the author adheres to the opinion as stated by i p gerasimov according to the latter pluvial stages in arid regions correspond to glaciations in the arcto boreal zone while xerothermal stages are synchronous to interglacials there are new paleofloristic evidence obtained in support of this opinion in particular it has been inferred from pollen spectra that during pluvial stages boreal flora including forest species penetrated into the caspian lowland turanian plain and to the black sea coast i e the regions of dry steppes and deserts at present at the xerothermal stages the typical steppe and desert landscapes of arid zone were restored

geomorphologic mapping of the lunar crater tycho and its impact melt deposits abstract using selene kaguya terrain camera and lunar reconnaissance orbiter camera lroc data we produced a new high resolution 10 m pixel geomorphological and impact melt distribution map for the lunar crater tycho the distal ejecta blanket and crater rays were investigated using lroc wide angle camera wac data 100 m pixel while the fine scale morphologies of individual units were documented using high resolution 0 5 m pixel lroc narrow angle camera nac frames in particular tycho shows a large coherent melt sheet on the crater floor melt pools and flows along the terraced walls and melt pools on the continuous ejecta blanket the crater floor of tycho exhibits three distinct units distinguishable by their elevation and hummocky surface morphology the distribution of impact melt pools and ejecta as well as topographic asymmetries support the formation of tycho as an oblique impact from the w sw the asymmetric ejecta blanket significantly reduced melt emplacement uprange and the depressed uprange crater rim at tycho suggest an impact angle of 25 45

weathering and anthropogenic influences on the water and sediment chemistry of wular lake kashmir himalaya this paper presents a study on the wular lake which is the largest fresh water tectonic lake of kashmir valley india one hundred and ninety six 196 water samples and hundred 100 sediment samples n 296 have been collected to assess the weathering and anthropogenic impact on water and sediment chemistry of the lake the results showed a significant seasonal variability in average concentration of major ions being highest in summer and spring and lower in winter and autumn seasons the study revealed that lake water is alkaline in nature characterised by medium total dissolved solids and electrical conductivity the concentration of the major ion towards the lake central showed a decreasing trend from the shore line the order of major cations and anions was ca2 mg2 na k and hco3 so4 2 cl respectively the geochemical processes suggested that the chemical composition lake water is mostly influenced by the lithology of the basin carbonates silicates and sulphates which had played a significant role in modifying the hydrogeochemical facies in the form of ca hco3 mg hco3 and hybrid type chemical index of alteration values of wular lake sediments reflect moderate weathering of the catchment area compared to upper continental crust and the post archean shale the sediments have higher si ti mg and ca contents and lower al fe na k p zn pb ni cu content geoaccumulation index igeo and us environmental protection agency sediment quality standards indicated that there is no pollution effect of heavy metals zn mn pb ni and co the study also suggested that wular lake is characterised by both natural and anthropogenic influences

geochemical and isotopic studies of groundwater conditions in the densu river basin of ghana the densu river basin drb is an important agricultural area in ghana and has a high population density water shortages have occurred in the basin due to drying out of surface water heavy pollution and low yield in most of the production wells which are crucial factors restricting sustainable socioeconomic development this study was carried out to investigate the geochemical characteristics and evolution as well as recharge processes in the drb system with regard to the tectonics geomorphology lithology and flow system it mainly used hydrochemistry environmental isotopes and a series of comprehensive data interpretation e g statistics ionic ratios and piper diagram to obtain a better understanding of the functioning of the system the following hydrochemical processes were identified as the main factors controlling the water quality of the groundwater system weathering of silicate minerals dissolution ion exchange and to a lesser extent evaporation which seems to be more pronounced downgradient of the flow system as groundwater flows from the recharge to discharge areas chemical patterns evolve in the order of ca2 hco3 ca2 mg2 hco3 to ca2 na cl ca2 na hco3 and na cl according to lithology the environmental isotope 18o 2h 3h measurements further revealed that groundwater in the drb was a relatively well mixed system as evidenced by the encoded narrow range of values however deviation from the rainwater signature indicates combined local processes such as direct percolation through preferential channels evaporation and probable surface water and anthropogenic contribution to the system

relative depths of simple craters and the nature of the lunar regolith abstract we assessed the morphologies of more than 930 simple impact craters diameters 40 m 10 km on the moon using digital terrain models dtms of a variety of terrains in order to characterize the variability of fresh crater morphology as a function of crater diameter from lunar reconnaissance orbiter camera lroc narrow angle camera nac dtms we determined depth to diameter d d ratios for an extremely fresh set of these craters with diameters less than 400 m and found that their d d ratios range from 0 11 to 0 17 using both nac and kaguya terrain camera dtms we also determined the d d ratios for the set of fresh simple craters larger than 400 m in diameter the d d ratios of these larger craters are typically near 0 21 as expected of gravity dominated crater excavation fresh craters less than 400 m in diameter on the other hand exhibit significantly lower d d ratios various possible factors affect the morphologies and relative depths d d ratios of small strength dominated craters including impactor and target properties e g effective strength strength contrasts porosity pre existing weaknesses impact angle and velocity and degradation state while impact conditions resulting from secondary impacts can also affect crater morphologies we found that d d ratio alone was not a unique discriminator of small secondary craters to investigate the relative influences of degradation and target properties on the d d ratios of small strength dominated craters we examined a subset of fresh craters located on the geologically young rim deposits of tycho crater these craters are deeper and steeper than other craters of similar diameter and degradation state consistent with their relative freshness and formation in the relatively coherent melt rich deposits in this region the d d ratios of globally distributed small craters of similar degradation state and size range on the other hand are relatively shallow with lower average wall slopes consistent with crater excavation in a weak or poorly cohesive layer the widespread predominance of these small shallow craters is consistent with the pervasive poorly cohesive upper regolith

geochemical isotopic and hydrological mass balance approaches to constrain the lake water groundwater interaction in dal lake kashmir valley it is important to have qualitative as well as quantitative understanding of the hydraulic exchange between lake and groundwater for effective water resource management dal a famous urban fresh water lake plays a fundamental role in social cultural and economic dynamics of the kashmir valley in this paper geochemical isotopic and hydrological mass balance approaches are used to constrain the lake water groundwater interaction of dal lake and to identify the sources of lake water water samples of precipitation n 27 lake water n 18 and groundwater n 32 were collected across the lake and its catchment for the analysis of 18o and 2h a total of 444 lake water samples and 440 groundwater samples springs tube wells and dug wells were collected for the analysis of ca2 mg2 hco3 so4 2 cl no3 na and k water table and lake water level were monitored at 40 observation locations in the catchment water table map including ph and ec values corroborate and verify the gaining nature of the dal lake stable isotopes of lake water in boddal and gagribal basins showed more deviation from the global meteoric water line than hazratbal and nigeen basins indicating the evaporation of lake water the isotopic and geochemical mass balance suggested that groundwater contributes a significant proportion 23 40 to dal lake the estimated average groundwater contribution to dal lake ranged from 31 2 103 to 674 103 m3 day 1 with an average of 276 103 m3 day 1 the study will be useful to delineate the possible sources of nutrients and pollutants entering the lake and for the management of lake water resources for sustainable development

mapping rays and secondary craters from the martian crater zunil 1 zunil a 10 1 km rayed crater in elysium planitia mars produced more than 7 107 secondary craters 15 m in diameter we mapped zunil s rays from thermal ir themis nighttime images up to 1700 km from the primary crater and mapped bright and dark ejecta craters candidate secondaries up to 3600 km range ray segments were mapped up to 450 km east of zunil and up to 1700 km to the west both rays and bright ejecta craters are best detected over terrains with moderate thermal inertia which are abundant west of but not east of zunil nevertheless our interpretation is that zunil was created by a moderately oblique impact from the east zunil secondaries are abundant over all terrain types except the medusae fossae formation mff given the likely age of zunil 100 ma parts of the mff must be eroding at 0 08 m ma the size frequency distribution of the secondaries in zunil s rays and probable distant secondaries 750 1700 km to the west of zunil have a cumulative power law exponent near 5 whereas secondaries between the major rays have an exponent near 3 4 we modeled the size velocity relationship for zunil s ejected fragments it is consistent with the predictions of melosh 1984 for spallation of a strong surface layer and demonstrates that the inverse size velocity correlation continues up to at least 2 km s