spatial distribution of volcanoes on io implications for tidal heating and magma ascent abstract extreme volcanism on io results from tidal heating but its tidal dissipation mechanisms and magma ascent processes are poorly constrained here we analyze the distribution of volcanic hotspots and paterae identified within the first 1 15 000 000 scale global geologic map of io to characterize their patterns of spatial organization ionian hotspots correspond to the locations of positive thermal anomalies that have been detected since 1979 whereas paterae are caldera like volcano tectonic depressions that record locations of volcanic activity over a longer period of geologic time up to 1 million years some 20 of patera floor units are associated with active hotspots but the majority appeared to be extinct or dormant at the time of observation volcano distributions are useful for testing interior models of io because the relative strength of tidal heating in the asthenosphere and deep mantle greatly affect expected patterns of surface heat flux we examine the spatial distribution of volcanic centers using nearest neighbor nn statistics and distance based clustering nearest neighbor analysis reveals that hotspots i e sites of active volcanism are globally random but closer to the equator they are uniform i e more widely spaced than a random model would predict this suggests that magma scavenging around active volcanic systems in the near equatorial region may drive hotspots apart whereas vigorous mantle convection and or deep mantle heating may reduce surface heat flux variations and promote spatial randomness on a global scale in contrast to the hotspots nn patera floor units tend to be clustered which implies that multiple eruptive units tend to form in association with most volcanic systems generalized paterae which represent volcanic systems tend to be uniformly distributed except in the northern regions where their distribution is random this implies that most volcanic systems interact with one another and repel except at high northern latitudes where they appear to form independently distance based clustering results support a dominant role for asthenospheric heating within io but show a 30 60 eastward offset in volcano concentrations from predicted locations of maximum surface heat flux along the tidal axis this offset may imply faster than synchronous rotation a role for lateral advection of magma within io s interior prior to its eruption state of stress controls on the locations of magma ascent and or a missing component in existing tidal dissipation models such as the effects of fluid tides generated within a globally extensive layer of interconnected partial melt

assessment of rock slope stability with the effects of weathering and excavation by comparing deterministic methods and slope stability probability classification sspc cut slopes are prone to fail due to the disturbance on original geometry and strength in addition because of these disturbances and stress relief natural apertures which increase the weathering effects widen in engineering time owing to these reasons slope stability assessment has a prominent role on these road cuts generally slope stabilities are assessed by deterministic approaches with a significant engineering judgment because of this reason the reputation of probabilistic approaches is increasing in this study 20 road cuts located in north west black sea region of turkey were evaluated using slope stability probability classification sspc considering this probabilistic approach rock strength parameters and failure mechanisms were determined furthermore slope mass rating smr classification was applied for each road cut in order to compare with the results obtained from sspc these overall results were then evaluated with the field observations considering rockslope deterioration assessment rda and falling rock hazard index frhi for the disturbed weathered zones and failure mechanisms according to these sspc is found to be more accurate for surficial degradations raveling and fall using samples taken from the disturbed weathered zones rather than using relatively fresh samples beyond the disturbed zone moreover despite strength differences between weathered and relatively fresh zones smr classification is identified to reveal the same stable probabilities it is found that sspc shows more detailed probabilistic results than smr lastly rockfall and raveling mechanisms determined by rda and rockfall risk by frhi were found to be coherent with sspc and field observations

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

pahoehoe toe dimensions morphology and branching relationships at mauna ulu kilauea volcano hawai i pahoehoe toe dimensions morphology and branching relationships were analyzed in flows emplaced during 1972 at mauna ulu a satellitic shield on the east rift zone of kilauea volcano hawai i in order to characterize regions within flow fields dominated by networks of pahoehoe toes measurements of toe length width thickness and orientation were completed for 445 toes at 13 sites variations in site characteristics including slope substrate and position in the flow field allow an evaluation of the effects of such parameters on toe dimensions toe surface morphology ropy or smooth local flow lobe position interior or margin and connective relationships between toes were documented in the form of detailed toe maps these maps show the number of branches connecting a given toe to other toes in its local pahoehoe network and illustrate branching patterns statistical analyses of toe dimensions and comparisons of pahoehoe toe study sites and sub populations combined with field observations evaluation of toe maps and qualitative examination of toe dimension size distributions show the following a although there are significant variations at a given site toes typically have mean lengths 101 cm greater than mean widths 74 cm and mean widths greater than mean thicknesses 19 cm sites that have mean widths greater than mean lengths are those with lower slopes b where significant site to site variations in mean values of a given toe dimension were apparent these differences could not be directly related to site characteristics c ropy toes have significantly larger mean values of length width and number of branches than smooth toes and toes with three or more branches have greater lengths widths and thicknesses than toes with two or fewer branches suggesting concentration of flow in these toe types d the skewness of all size distributions of toe length and width to larger values suggests that toes are transitional to larger sheets and channels consistent with field observations and e two distinct types of branching patterns called monolayer and centrally ridged were observed in preserved pahoehoe flow lobes the significant variability in measured toe dimensions at mauna ulu suggests that toe dimensions are influenced by numerous locally defined random factors and that an approach based on stochastic methods can be used to model pahoehoe flow emplacement

possible pingo fields in the utopia basin mars geological and climatical implications abstract the presence of pingos on mars has been hypothesized since the period of the viking mission in fact a diverse range of pingo like features has been found at various martian sites including elysium chryse and utopia planitiae in the northern lowlands due to the morphology and the geological setting some of those features were interpreted in different ways creating some controversies as happened in athabasca valles this reflects the complexity of interpreting these features by remote sensing and multiple plausible interpretations of the same feature with the objective of identifying new possible pingos or rootless cones on mars we selected a study area in utopia planitia 10 55 n 210 260 w where the presence of both features is possible due to its geological history volcanic and hydrological we analyzed more than 2100 mars orbiter camera moc narrow angle images in addition to viking thermal emission imaging system themis and high resolution stereo camera hrsc images together with mars orbiter laser altimeter mola derived digital elevation models dems with a geographic information system gis we found in 94 moc narrow angle images dome cone and ring shaped features we analyzed them from morphological and morphometrical points of view in order to compare them with relevant features on mars and earth we tested different possible origins for those features following the approach of multiple working hypotheses we conclude that the dome cone and ring shaped features could be pingos which is in agreement with their geological settings regarding the driving heat source for the formation of the purported pingos we propose the existence of a heat source possibly a magma chamber underneath the surface of the utopia basin together with possible climatic shifts the past activities of the heat source may have caused melting of ground ice the pingo growth due to freezing of the water would have occurred during the following cold climatic conditions

millennial scale variability in the asian monsoon evidence from oxygen isotope records from stalagmites in southeastern china abstract two stalagmites from xiangshui x3 and yaoba don yb1 caves in southeastern china provide high resolution 18o time series that exhibit prominent millennial scale fluctuations in the intensity and character of the asian monsoon for the period from 20 000 to 50 000 yr b p timing of these fluctuations established by u series disequilibrium 230th 234u correlates with dansgaard oeschger events 2 13 and heinrich events h2 h5 recorded in the gisp2 ice core indicating a climatic link between asian monsoon circulation and air temperatures over the north atlantic for much of the last glaciation although the exact mechanisms linking climatic fluctuations in the north atlantic to those in eastern china have yet to be identified climatic signals associated with changes in global ice volume and air temperatures over greenland may be transferred to asia by atmospheric mechanisms that affect the strength of the siberian high pressure cell and the amount of snow cover on the tibetan plateau which force the intensity of the asian monsoon another mechanism linking climate of the north atlantic to the asian monsoon relates to variation in oceanic circulation millennial scale fluctuations in thermohaline circulation in the north atlantic may have affected ocean currents in the tropical western pacific ocean which is the moisture source for the east asian monsoon despite the similarity of these paleoclimatic records and the implication of global teleconnections the magnitude and timing of millennial scale events at different locations in china reveal regional variations in climatic conditions comparisons of the 18o curves from xiangshui and yaoba don cave stalagmites with those from qixin cave and hulu cave show general concordance between millennial scale events albeit with some notable differences among all the records the well studied hulu cave records show 18o values that are lower than those of xiangshui and yaoba don caves reflecting geographical differences hulu cave is located near the eastern coast at a relatively low elevation dominated by the east asian monsoon by comparison xiangshui cave and yaoba don cave are further inland on the eastern slope of the yunnan guizhou plateau which receives precipitation from both the east asian monsoon and quasi stationary frontal systems rainfall contributed by the east asian summer monsoon is relatively diminished in this region by these geographic and atmospheric circulation conditions resulting in higher 18o values

insights into corona formation through statistical analyses 1 statistical analysis of an expanded database of coronae on venus indicates that the populations of type 1 with fracture annuli and 2 without fracture annuli corona diameters are statistically indistinguishable and therefore we have no basis for assuming different formation mechanisms analysis of the topography and diameters of coronae shows that coronae that are depressions rimmed depressions and domes tend to be significantly smaller than those that are plateaus rimmed plateaus or domes with surrounding rims this is consistent with the model of smrekar and stofan 1997 and inconsistent with predictions of the spreading drop model of koch and manga 1996 the diameter range for domes the initial stage of corona formation provides a broad constraint on the buoyancy of corona forming plumes coronae are only slightly more likely to be topographically raised than depressions with type 1 coronae most frequently occurring as rimmed depressions and type 2 coronae most frequently occurring with flat interiors and raised rims most type 1 coronae are located along chasmata systems or fracture belts while type 2 coronae are found predominantly as isolated features in the plains coronae at hot spot rises tend to be significantly larger than coronae in other settings consistent with a hotter upper mantle at hot spot rises and their active state

modification of slope mass rating smr by continuous functions this study was partially funded by the spanish ministry of science and technology and feder project tec 2005 06863 by the valencia regional government project gv06 179 and grupos03 085 and by the university of alicante project vigrob 157

glacial interglacial variation in catchment weathering and erosion paces the indian summer monsoon during the pleistocene abstract silicate weathering via co2 consumption is considered to regulate the long term climate change discriminating silicate versus carbonate weathering from sedimentary records is helpful to understand the coupling relationship between weathering and past climate however owing to the paucity of well dated and continuous records of weathering and erosion the relationship between silicate and carbonate weathering and their links with mountain uplift and glacial interglacial climate remain elusive geochemical analysis of a 666 m core from the heqing basin a paleolake situated at the southeastern margin of the tibetan plateau demonstrates silicate versus carbonate weathering and erosion changes under indian summer monsoon ism conditions spanning the entire pleistocene via respective tracing between rb sr and al na ratios the rb sr record is interpreted as reflecting a competition between clayey silicate origin rb versus carbonate origin sr fluxes whereas al na ratio is a balance between weathering and erosion of silicate minerals both pacing the glacial interglacial cycles of the ism during interglacials strong silicate weathering intensity reflected by low al na values is mainly controlled by warmer temperatures with the reduced variability during 1 82 0 92 ma recalling the pacing of the arabian sea surface temperature amplitudes within glacials the weak carbonate leaching and clay erosion within the older and younger intervals are interrupted by strong clay erosion within the middle interval in conclusion the heqing rb sr and al na records reveal the sensitivity of catchment weathering and erosion to ism changes over glacial interglacial timescales with warmer temperature enhancing silicate weathering and clay formation during interglacials and greater physical erosion during glacials

orogeny and orography the effects of erosion on the structure of mountain belts a numerical model of the coupled processes of tectonic deformation and surface erosion in convergent orogens is developed to investigate the nature of the interaction between these processes crustal deformation is calculated by a two dimensional finite element model of deformation in response to subduction and accretion of continental crust erosion operates on the uplifted surface of this model through fluvial incision which is taken to be proportional to stream power the relative importance of the tectonic and erosion processes is given by a dimensionless erosion number relating convergence velocity rock erodibility and precipitation rate this number determines the time required for a system to reach steady state and the final topographic shape and size of a mountain belt fundamental characteristics of the model orogens include asymmetric topography with shallower slopes facing the subducting plate and an asymmetric pattern of exhumation with the deepest levels of exhumation opposite to subduction these characteristics are modified when the regional climate exhibits a dominant wind direction and orographically enhanced precipitation on one side of the mountain belt the two possible cases are dominant wind in the direction of motion of the subducting plate and dominant wind direction in the opposite direction of the subducting plate velocity models of the former case predict a broad zone of exhumation with maximum exhumation in the orogen interior models of the latter case predict a focused zone of exhumation at the margin of the orogen and at high erosion number a reversal in the topographic asymmetry natural examples of these two cases are presented the southern alps of new zealand exhibits the climate and exhumation asymmetry characteristic of wind in the direction opposite to motion of the subducting plate the asymmetry of topography suggests that erosion is not efficient enough to have reversed the topographic asymmetry the contrasting example of dominant wind in the direction of subduction motion is provided by the olympic mountains of washington state in this case exhumation of deep levels of the cascadia accretionary wedge shows a broad domal pattern consistent with the observed orographic precipitation

geomorphology mountains and monsoons the influence of climate on mountain building has long been debated a reconstruction for the past 25 million years suggests coincidence of himalayan erosion and monsoon intensification hinting at a causal relationship

effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments with implications for provenance studies the bulk chemical compositions mineralogy and mineral proportions of sands and muds of the mallacoota basin in southeastern australia reflect the composition of weathering profiles mantling source rocks rather than bedrock muds contain abundant clay minerals that are virtually absent from the source rocks but abundant in the weathering profiles sands are strongly enriched in quartz relative to source rocks even in the headwaters of the fluvial system demonstrating that feldspar destruction occurs by in situ chemical weathering within profiles and before detritus enters the fluvial system k feldspar is proportionally more abundant in fluvial sands than in source rocks because plagioclase is more rapidly destroyed than either quartz or k feldspar in weathering profiles subsequent erosion and sorting produce sands enriched in quartz with high k feldspar plagioclase ratios relative to source rocks the composition of plagioclase incorporated into the fluvial sands is also controlled by chemical weat

identification of volcanic rootless cones ice mounds and impact craters on earth and mars using spatial distribution as a remote sensing tool 1 this study aims to quantify the spatial distribution of terrestrial volcanic rootless cones and ice mounds for the purpose of identifying analogous martian features using a nearest neighbor nn methodology we use the statistics r ratio of the mean nn distance to that expected from a random distribution and c a measure of departure from randomness we interpret r as a measure of clustering and as a diagnostic for discriminating feature types all terrestrial groups of rootless cones and ice mounds are clustered r 0 51 0 94 relative to a random distribution applying this same methodology to martian feature fields of unknown origin similarly yields r of 0 57 0 93 indicating that their spatial distributions are consistent with both ice mound or rootless cone origins but not impact craters each martian impact crater group has r 1 00 i e the craters are spaced at least as far apart as expected at random similar degrees of clustering preclude discrimination between rootless cones and ice mounds based solely on r values however the distribution of pairwise nn distances in each feature field shows marked differences between these two feature types in skewness and kurtosis terrestrial ice mounds skewness 1 17 1 99 kurtosis 0 80 4 91 tend to have more skewed and leptokurtic distributions than those of rootless cones skewness 0 54 1 35 kurtosis 0 53 1 13 thus nn analysis can be a powerful tool for distinguishing geological features such as rootless cones ice mounds and impact craters particularly when degradation or modification precludes identification based on morphology alone

coal mining under difficult geological conditions the can lignite open pit canakkale turkey abstract this paper describes the slope instability problems in the can canakkale northwestern turkey coal mine slope instabilities have been one of the major problems in the pit mine since the beginning of mining activities in particular the west and east sector panels in front of the tki turkish coal enterprises buildings and the seramic factory located in the vicinity of the pit mine have been suffering from slope instability problems to assess the instabilities field data collection from boreholes surface sampling and monitoring studies were performed deterministic stability analyses such as limit equilibrium sensitivity and back analyses were applied based on the results the active passive wedge type of failure was determined as the most dominant instability type based on the back analysis results mean values of residual shear strength parameters were determined as c 42 kpa o 8 the results also indicate that the excessive excavation of the toe along the huge lignite open pit was the main cause of the instability the weak contacts between the lithological units were also an important factor taking into consideration the results of the analyses some remedial measures were also suggested for the coal mine such as decreasing the inclination of the toe safe benching and effective drainage of surface water and groundwater

using satellite imagery to identify and analyze tumuli on earth and mars abstract tumuli are small dome like features that form when magmatic pressures build within a subsurface lava pathway causing the overlying crust to bulge upwards as the appearance of these features has been linked to lava flow structure e g underlying lava flow tubes and conditions there is interest in identifying such features in satellite images so they can be used to expand our understanding of lava flows within regions difficult to access such as on other planets here we define a methodology for identifying and measuring tumuli within satellite imagery and validate it by comparing our results with fieldwork results of terrestrial tumuli reported in the literature and with independent measurements we made within amboy field ca in addition we present aggregated results from the application of our methodology to satellite images of six terrestrial fields and seven martian fields with 2100 tumuli identified per planet comparisons of tumuli morphometrics on earth and mars yield similarities in size and overall shape which were surprising given the many differences in the environmental and planetary conditions within which these features have formed given our measurements we identify constraints for tumulus formation models and drivers that would yield similar shapes and sizes on two different planets furthermore we test a published hypothesis regarding the number of tumuli that form per a square kilometer and find it unlikely that a diagnostic tumuli density value exists

clustering within rootless cone groups on iceland and mars effect of nonrandom processes 1 this study aims at quantifying the spatial distribution of cones within rootless cone groups rcgs our data set consists of 1 seven icelandic rcgs identified through field investigations 2 seven candidate rcgs on mars identified through mars orbiter camera moc and thermal emission imaging system themis images and 3 four groups of impact craters on mars also identified through moc and themis images to determine if they can be remotely distinguished from the rcgs purely on the basis of their spatial distribution several independent statistical techniques are used including nearest neighbor analysis analysis of variance anova and linear alignment detection analysis our results indicate that the spatial distribution of each rcg is not random within a cone group cones preferentially form near existing cones the presence of at least one significant linear cone alignment in each rcg and strong linear alignments in some groups suggests that rootless cones form as the surface signature of preferred lava pathways an anova on mean nearest neighbor distances reveals the martian cone groups to be statistically indistinguishable from the icelandic rcgs supporting existing interpretations that they represent rootless cone groups a similar anova showed that the martian cone groups do not resemble the martian impact crater clusters studied the impact craters have significantly greater nearest neighbor distances and show no evidence of aggregation within a crater group

nearest neighbor analysis of small features on mars applications to tumuli and rootless cones 1 fields of low relief cones domes and mounds on mars have been interpreted as tumuli rootless cones and pingos the spatial distribution of such features can be characterized by their nearest neighbor nn distances the nn distributions can provide insight into the physical processes that affected field formation and can possibly provide a future diagnostic of the feature type present on mars the conventional approach for analyzing the observed nn distribution is based on the poisson probability distribution and uses one statistic c our simulations of spatial randomness show that there is an unrecognized bias in c that often leads to erroneous conclusions three alternative extensions of the poisson distribution are proposed here the first accounts for a minimum threshold on the size of features discerned the second considers the scavenging of the resources necessary to form neighboring features e g inflation pressurization and subsurface volatiles and the third models self limiting growth of the feature population three statistical tests are proposed to improve the conventional nn analysis we provide the critical regions needed to perform these tests for common sample sizes of these geologic features our methodology is applied to tumuli at mauna ulu hawaii and conjectured tumuli and rootless cones on mars each example exhibits a different aspect of spatial randomness these applications suggest avenues for further field and theoretical studies to develop this approach as a remote sensing diagnostic

simulation of inflated pahoehoe lava flows a new stochastic model simulates late stage pahoehoe lobes where random processes dominate emplacement the model prescribes probabilistic rules for determining where and when parcels of lava move within the lobe unlike a classical brownian motion random walk the model allows individual parcels to remain dormant but fluid for multiple time steps the randomness of parcel volume transfers within the lobe interior as well as at the margins qualitatively reflects inflation processes observed in the field the fraction of inflated volume to total volume increases with the total volume with greater than 75 of the lobe volume contributed through inflation for typical lobes the influence on planform shape and topographic cross sectional profiles of total volume source area and shape topographic confinement and sequential breakouts at the lobe margins are all explored with the stochastic model each of these factors influences the overall lobe thickness and width the model provides a means for assessing the relative importance of these processes through comparisons with field data for the first time gaussian and parabolic functions are quantitatively fit to field measurements of pahoehoe lobes both functional forms provide adequate description of the cross sectional flow shapes when comparing simulated lobes to field data sequential breakouts at the lobe margins are found to be an important process controlling the final topographic distribution of observed pahoehoe lobes

correlation of himalayan exhumation rates and asian monsoon intensity although most data suggest that the india eurasia continental collision began 45 55 myr ago the architecture of the himalayan tibetan orogen is dominated by deformational structures developed in the neogene period 23 myr ago the stratigraphic record and thermochronometric data indicate that erosion of the himalaya intensified as this constructional phase began and reached a peak around 15 myr ago it remained high until 10 5 myr ago and subsequently slowed gradually to 3 5 myr ago but then began to increase once again in the late pliocene and pleistocene epochs here we present weathering records from the south china sea bay of bengal and arabian sea that permit asian monsoon climate to be reconstructed back to the earliest neogene these indicate a correlation between the rate of himalayan exhumation as inferred from published thermochronometric data and monsoon intensity over the past 23 myr we interpret this correlation as indicating dynamic coupling between neogene climate and both erosion and deformation in the himalaya although the india eurasia collision initiated 50 myr ago major deformation and exhumation of the himalaya did not begin until the early neogene 23 myr ago this coincides with the increased intensity of the asian monsoons as indicated by weathering records from the south china sea bay of bengal and arabian sea and hints at a dynamic coupling between climate and both erosion and deformation in the himalaya

statistical distribution of tumuli on pahoehoe flow surfaces analysis of examples in hawaii and iceland and potential applications to lava flows on mars 1 spatial distributions of tumuli on lava flow surfaces can be quantitatively linked to subsurface inflation processes three distinct styles of flow emplacement are studied 1 lava flows undergo inflation that changes as a function of space and time resulting in random spatial distributions of tumuli 2 lava flows with preferred pathways result in systematic clustering of inflation features and 3 established tubes or narrow pahoehoe flows produce chains of tumuli statistical analyses are required to distinguish between styles one and two comparison of the spatial distribution of tumuli on a portion of a lava flow at mauna ulu with the poisson distribution indicates that tumuli are randomly distributed on the flow surface typical of style one emplacement where small scale topographic variability and low slope influence development of preferred pathways that evolve over time at thrainsskjoldur direct statistical comparisons to the poisson spatial distribution are inconclusive but nearest neighbor analysis indicates significant clustering an initially random spatial distribution is inferred that developed preferred pathways and systematic clustering of inflation features as with style two at elysium planitia on mars the flow margin is significantly deficient in inflation features while away from the margin the flow exhibits a random spatial distribution of tumuli typical of style one emplacement the flow is interpreted as multiple units or a single flow that migrated in space during emplacement at the 1843 flow on mauna loa tumuli occur on a linear trend consistent with style three emplacement

composition and location of volatiles at loki patera io abstract volatiles play a critical role in determining the nature of volcanic activity on earth but their role in the volcanism on io is less clear to help determine that role we analyze voyager and galileo images of loki patera loki is the largest caldera in the solar system and io s most powerful volcano however its eruptive behavior is still not understood it appears to be relatively volatile poor in comparison to other sites like pele where volatiles drive a 350 km high plume a resurfacing wave either from spreading flows or from foundering of a lava lake crust periodically sweeps around loki patera photometry from voyager i and ii violet and blue images shows that most of the features in and around loki have colors well matched by macroscopic mixing of sulfur and basalt the dark western portion of the patera has the color of bare basalt assuming such a macroscopic sulfur basalt mix in the voyager i images most of the rest of the patera appears to be covered with a background of 13 38 sulfur we infer this background sulfur was deposited from the nearby plume observed by voyager i and ii the surface of the patera is also dotted by numerous small bright areas which have colloquially been called bergs we find that they are also composed of sulfur with coverage ranging up to 100 darker regions adjacent to the patera such as the southwest overflow are a mixture of intermediate amounts of sulfur and basalt the bathtub ring at the edge of the overflow is again roughly 100 sulfur perhaps with significant amounts of so 2 included colors seen during the voyager ii flyby are also consistent with this general pattern but most of the patera has a sulfur abundance higher than that seen in voyager i while the then dark southern portion is again close to the reflectance of bare basalt we have also analyzed the spatial distribution of the bergs they clearly avoid the inner and outer margins of the patera and they also avoid each other while a simple explanation of the above patterns could be that the bergs are fumarolic sulfur deposited on a periodically resurfaced lava lake crust other observations seem inconsistent with that simple model careful comparison of voyager i and galileo data shows that the largest bergs in the southern patera have survived the intervening 22 years this requires that at least those larger bergs represent some more permanent feature perhaps higher standing kipuka which avoid inundation by the lava resurfacing wave

fluids mobilization in arabia terra mars depth of pressurized reservoir from mounds self similar clustering abstract arabia terra is a region of mars where signs of past water occurrence are recorded in several landforms broad and local scale geomorphological compositional and hydrological analyses point towards pervasive fluid circulation through time in this work we focus on mound fields located in the interior of three casters larger than 40 km firsoff kotido and unnamed crater 20 km to the east and showing strong morphological and textural resemblance to terrestrial mud volcanoes and spring related features we infer that these landforms likely testify the presence of a pressurized fluid reservoir at depth and past fluid upwelling we have performed morphometric analyses to characterize the mound morphologies and consequently retrieve an accurate automated mapping of the mounds within the craters for spatial distribution and fractal clustering analysis the outcome of the fractal clustering yields information about the possible extent of the percolating fracture network at depth below the craters we have been able to constrain the depth of the pressurized fluid reservoir between 2 5 and 3 2 km of depth and hence we propose that mounds and mounds alignments are most likely associated to the presence of fissure ridges and fluid outflow their process of formation is genetically linked to the formation of large intra crater bulges previously interpreted as large scale spring deposits the overburden removal caused by the impact crater formation is the inferred triggering mechanism for fluid pressurization and upwelling that through time led to the formation of the intra crater bulges and after compaction and sealing to the widespread mound fields in their surroundings

the importance of pahoehoe abstract pahoehoe lava flows are common in every basaltic province and their submarine variants pillow lavas and sheet flows cover the bulk of the earth pahoehoe flows are emplaced by inflation the injection of molten lava underneath a solidified crust only in the past few years has an understanding of the inflation process and the ability to recognize ancient inflated lava flows been achieved all large terrestrial basaltic flow fields studied to date including flood basalts were emplaced as thermally efficient inflated compound pahoehoe sheet flows this leads us to propose that this is the standard way of emplacing large lavas the swell hypothesis the atmospheric impact of such flood basalt eruptions could have been protracted and severe providing a plausible link between flood basalt eruptions and mass extinctions

a discussion on the adjustment parameters of the slope mass rating smr system for rock slopes abstract rock mass classification systems are common tools used in the design and construction of rock engineering numerous classification systems have been developed for rock slopes of which the slope mass rating smr system is the most popular consequently many rock slope classification systems have been derived from the smr system however these systems are not good at determining the values of the two adjustment parameters f 1 and f 3 implying that the original smr system may contain theory defects in this paper we propose some corrected methods for determining f 1 and f 3 and perform a series of analyses considering the three failure modes of rock slopes plane wedge and toppling failures the results of the discrepancy analysis from f 1 illustrate that with respect to each of the aforementioned three failure modes the calculated original smr index is larger than or equal to the real value and the designed slope is possibly in danger the results of the discrepancy caused by the f 3 illustrate that for each of the aforementioned three failure modes the calculated original smr index is smaller than or equal to the real value and the designed slope might be conservative and not economical

rootless cones on mars indicating the presence of shallow equatorial ground ice in recent times high resolution mars orbiter camera moc images have revealed the existence of clusters of small cones in the cerberus plains marte valles and amazonis planitia mars these cones are similar in both morphology and planar dimensions to the larger of icelandic rootless cones which form due to explosive interactions between surficial lavas and near surface groundwater impact crater size frequency relationships indicate that surfaces upon which the cones sit are no older than 10 ma if martian cones form in the same manner as terrestrial rootless cones then equatorial ground ice or ground water must have been present near the surface in geologically recent times

emplacement and inflation of pahoehoe sheet flows observations and measurements of active lava flows on kilauea volcano hawaii inflated pahoehoe sheet flows have a distinctive horizontal upper surface which can be several hundred meters across and are bounded by steep monoclinal uplifts the inflated sheet flows we studied ranged from 1 to 5 m in thickness but initially propagated as thin sheets of fluid pahoehoe lava generally 20 30 cm thick individual lobes originated at outbreaks from the inflated front of a prior sheet flow lobe and initially moved rapidly away from their source velocities slowed greatly within hours due to radial spreading and to depletion of lava stored within the source flow as the outward flow velocity decreases cooling promotes rapid crustal growth at first the crust behaves plastically as pahoehoe toes form after the crust attains a thickness of 2 5 cm it behaves more rigidly and develops enough strength to retain incoming lava thus increasing the hydrostatic head at the flow front the increased hydrostatic pressure is distributed evenly through the liquid lava core of the flow resulting in uniform uplift of the entire sheet flow lobe initial uplift rates are rapid flows thicken to 1 m in 1 2 hours but rates decline sharply as crustal thickness increases and as outbreaks occur from the margins of the inflating lobe one flow reached a final thickness of nearly 4 m after 350 hr inflation data define power law curves whereas crustal cooling follows square root of time relationships the combination of data can be used to construct simple models of inflated sheet flows as the flow advances preferred pathways develop in the older portions of the liquid cored flow these pathways can evolve into lavatube systems within a few weeks formation of lava tubes results in highly efficient delivery of lava at velocities of several kilometers per hour to a flow front that may be moving 1 2 orders of magnitude slower if advance of the sheet flow is terminated the tube remains filled with lava that crystallizes in situ rather than draining to form the cave like lava tubes commonly associated with pahoehoe flows inflated sheet flows from kilauea and mauna loa are morphologically similar to some thick icelandic and submarine sheet flows suggesting a similar mechanism of emplacement the planar sheet like geometry of flood basalt flows may also result from inflation of sequentially emplaced flow lobes rather than nearly instantaneous emplacement as literal floods of lava

lithological types and envirogeotechnical characteristics of the waikato coal measures new zealand abstract a pictorial guide of cored rocks in the waikato coal fields new zealand with associated geotechnical and envirotechnical characteristics has been prepared the methodology results including facies interpretation and use by mining personnel are discussed in this paper rock coring is widely conducted in most of the world s active coal fields this exploration method although the most costly is the most complete record of the subsurface geology at any particular location unfortunately much of this potentially valuable information is lost due to the incomplete description of the rock recovered from the core hole in some cases the description is adequate but errors and confusion may arise from a lack of uniform terminology it is the objective of this guide to provide a standard base for core description with a consistent set of terms to describe the rock and coal core the guide contains a set of colour photographs of cores of the common rock types and coal in the waikato coal measures each sample is given a name and a three or four digit number which convey characteristics such as the grain size colour and sedimentary structure the photographs are grouped into major classes that are accompanied by short texts describing the properties that are useful in differentiating rock types

landslide susceptibility assessment using logistic regression and its comparison with a rock mass classification system along a road section in the northern himalayas india landslide studies are commonly guided by ground knowledge and field measurements of rock strength and slope failure criteria with increasing sophistication of gis based statistical methods however landslide susceptibility studies benefit from the integration of data collected from various sources and methods at different scales this study presents a logistic regression method for landslide susceptibility mapping and verifies the result by comparing it with the geotechnical based slope stability probability classification sspc methodology the study was carried out in a landslide prone national highway road section in the northern himalayas india logistic regression model performance was assessed by the receiver operator characteristics roc curve showing an area under the curve equal to 0 83 field validation of the sspc results showed a correspondence of 72 between the high and very high susceptibility classes with present landslide occurrences a spatial comparison of the two susceptibility maps revealed the significance of the geotechnical based sspc method as 90 of the area classified as high and very high susceptible zones by the logistic regression method corresponds to the high and very high class in the sspc method on the other hand only 34 of the area classified as high and very high by the sspc method falls in the high and very high classes of the logistic regression method the underestimation by the logistic regression method can be attributed to the generalisation made by the statistical methods so that a number of slopes existing in critical equilibrium condition might not be classified as high or very high susceptible zones

explosive lava water interactions ii self organization processes among volcanic rootless eruption sites in the 1783 1784 laki lava flow iceland we have applied quantitative geospatial analyses to rootless eruption sites in the hnuta and hrossatungur groups of the 1783 1784 laki lava flow to establish how patterns of spatial distribution can be used to obtain information about rootless cone emplacement processes and paleo environments this study utilizes sample size dependent nearest neighbor nn statistics and voronoi tessellations to quantify the spatial distribution of rootless eruption sites and validate the use of statistical nn analysis as a remote sensing tool our results show that rootless eruption sites cluster in environments with abundant lava and water resources but competition for limited groundwater in these clusters can cause rootless eruption sites to develop repelled distributions this pattern of self organization can be interpreted within the context of resource availability and depletion topography tends to concentrate lava fuel and water coolant within topographic lows thereby promoting explosive lava water interactions in these regions given an excess supply of lava within broad sheet lobes rootless eruption sites withdraw groundwater from their surroundings until there is insufficient water to maintain analogs to explosive molten fuel coolant interactions rootless eruption sites may be modeled as a network of water extraction wells that draw down the water table in their vicinity rootless eruptions at locations with insufficient groundwater may either fail to initiate or terminate before explosive activity has ceased at nearby locations with a greater supply of water thus imparting a repelled distribution to observed rootless eruption sites

explosive lava water interactions in elysium planitia mars geologic and thermodynamic constraints on the formation of the tartarus colles cone groups 1 volcanic rootless constructs vrcs are the products of explosive lava water interactions vrcs are significant because they imply the presence of active lava and an underlying aqueous phase e g groundwater or ice at the time of their formation combined mapping of vrc locations age dating of their host lava surfaces and thermodynamic modeling of lava substrate interactions can therefore constrain where and when water has been present in volcanic regions this information is valuable for identifying fossil hydrothermal systems and determining relationships between climate near surface water abundance and the potential development of habitable niches on mars we examined the western tartarus colles region 25 27 n 170 171 e in northeastern elysium planitia mars and identified 167 vrc groups with a total area of 2000 km2 these vrcs preferentially occur where lava is 60 m thick crater size frequency relationships suggest the vrcs formed during the late to middle amazonian modeling results suggest that at the time of vrc formation near surface substrate was partially desiccated but that the depth to the midlatitude ice table was 42 m this ground ice stability zone is consistent with climate models that predict intermediate obliquity 35 between 75 and 250 ma with obliquity excursions descending to 25 32 for lava thicknesses ranging from 30 to 60 m and ground ice fractions ranging from 0 1 to 0 3 an ice volume of 4 23 km3 could have been melted and or vaporized by the time the lava solidified and the associated hydrothermal systems could have retained temperatures 273 k for up to 1300 years

surface uplift uplift of rocks and exhumation of rocks uplift of the surface of mountain belts requires forces that are comparable in magnitude to those associated with plate motion and therefore determination of rates of surface uplift could provide important information on the dynamics of mountain ranges rates of uplift of the surfaces of mountain ranges have not however been quantified sufficiently well that they provide useful constraints on those processes many reports off surface uplift in mountain ranges are based on mistaking exhumation of rocks or uplift of rocks for surface uplift and provide no information whatsoever on the rates of surface uplift

himalayan tectonics explained by extrusion of a low viscosity crustal channel coupled to focused surface denudation recent interpretations of himalayan tibetan tectonics have proposed that channel flow in the middle to lower crust can explain outward growth of the tibetan plateau1 2 3 and that ductile extrusion of high grade metamorphic rocks between coeval normal and thrust sense shear zones can explain exhumation of the greater himalayan sequence4 5 6 7 here we use coupled thermal mechanical numerical models to show that these two processes channel flow and ductile extrusion may be dynamically linked through the effects of surface denudation focused at the edge of a plateau that is underlain by low viscosity material our models provide an internally self consistent explanation for many observed features of the himalayan tibetan system8 9 10

a stochastic basis to the spatially uniform distribution of randomly generated ionian paterae due to its tidally heated interior io is a geologically very active satellite that bears many volcanic features it is observed that the mean nearest neighbor distance of each volcanic feature called a patera is larger than that of a random distribution which implies that the spatial distribution of paterae is uniform rather than random however it is uncertain how the paterae are organized into a uniform distribution we suggest the mechanism of io s uniformly distributed paterae considering localized obliteration of old features instead of geological modeling we performed stochastic simulations and statistical analyses for the obliteration of quiescent paterae monte carlo calculations with gaussian obliteration probability show that if the width of obliteration probability is approximately 80 km and the volcanic generation rate is 5 0 10 6 km 2 ma 1 uniform distribution and the observed number density of paterae are attained at the 2 level on a timescale of approximately 6 million years with this generation rate and width of the obliteration probability the averaged distance of one patera to the nearest patera mean nearest neighbor distance is approximately 200 km which is consistent with the observed value the uniformity of the distribution is maintained once it is achieved on regional scales io s paterae would naturally evolve from random into uniform distributions by the obliteration of old and quiescent features

the volcanic history of syria planum mars abstract a field of small 10s of km in diameter volcanoes in the syria planum region of mars is mapped to determine abundance distribution and alignments of vents these data are used to assess possible variations in eruption style across space and time each eruption site is assigned a point location nearest neighbor and two point azimuth analyses are conducted to assess the spacing and orientations between vents across the study area two vent fields are identified as unique volcanic units along with the previously identified syria mons volcano superposition relationships and crater retention rates indicate that these three volcanic episodes span 900 ma beginning in the early hesperian and ending in the early amazonian no clear hiatus in eruptive activity is identified between these events although a progression from eruptions at syria mons to regionally distributed eruptions that form the bulk of the syria planum plains to a final migration of dispersed eruptions to syria s northwest is identified nearest neighbor analyses suggest a non random distribution among the entire population of syria planum which is interpreted as resulting from the interaction of independent magma bodies ascending through the crust during different stress regimes throughout the region s eruptive history two point azimuth results identify three orientations of enhanced alignments which match well with radial extensions of three major tectonic centers to the south east and northwest of the study area as such syria planum volcanism evolved from a central vent volcano to dispersed shield field development over several hundred million years during which the independent magma bodies related to each small volcano interacted to some extent with one or more of at least three buried tectonic patterns in the older crust these results show a strong relationship between independent mapping efforts of tectonic and volcanic features continued integration of volcano tectonic mapping should provide direct constraints for future geodynamic models of magma production and thermal evolution of the tharsis province

rootless cones on mars a consequence of lava ground ice interaction fields of small cratered cones on mars are interpreted to have formed by rootless eruptions due to explosive interaction of lava with ground ice contained within the regolith beneath the flow melting and vaporization of the ice and subsequent explosive expansion of the vapour act to excavate the lava and construct a rootless cone around the explosion site similar features are found in iceland where flowing lava encountered water saturated substrates the martian cones have basal diameters of c 30 1000 m and are located predominantly in the northern volcanic plains high resolution mars orbiter camera images offer significant improvements over viking data for interpretation of cone origins a new model of the dynamics of cone formation indicates that very modest amounts of water ice are required to initiate and sustain the explosive interactions that produced the observed features this is consistent with the likely low availability of water ice in the martian regolith the scarcity of impact craters on many of the host lava flows indicates very young ages suggesting that ground ice was present as recently as less than 10 l00 ma and may persist today rootless cones therefore act as a spatial and temporal probe of the distribution of ground ice on mars which is of key significance in understanding the evolution of the martian climate the location of water in liquid or solid form is of great importance to future robotic and human exploration strategies and to the search for extraterrestrial life

messinian climate change and erosional destruction of the central european alps at the end of the miocene the european alps ceased outward expansion and tectonic uplift and exhumation shifted into the orogen interior this shift is consistent with a change from orogenic construction to orogenic destruction reflecting an increase in the ratio of erosional flux to accretionary flux the coincidence of this change with an increase in sediment yield from the alps suggests a climate driven increase in erosional flux the timing of deformation and sediment release from the southern alps indicates that the tectonic change occurred synchronous with the last phase of the messinian salinity crisis we attribute the increase in erosional flux to a climatic shift to wetter conditions throughout europe likely augmented by the base level fall that occurred during the mediterranean dessication this climate change is represented in the stratigraphic record by the lago mare deposits of the mediterranean salinity crisis

coronae of parga chasma venus 1 parga chasma is a 10 000 km long fracture and trough system in the southern hemisphere of venus in this study we analyze coronae in the parga region addressing the relationship between corona and rift formation the relationship of volcanism to rifting and coronae and the overall evolution of the rift system our observations are compared with various models with the aim of determining any causative relationships between corona formation volcanism and rifting our statistical analysis shows that coronae are randomly located within this region indicating that corona locations are not significantly controlled by rifting or by lithospheric loading caused by the earlier formation of other coronae our observations suggest that the two processes of corona and rift formation were occurring more or less synchronously with no specific control on each other but that coronae and rifting in this region are genetically related we find a wide variation in the amount of volcanism associated with coronae across the parga region and no evidence for a deep seated plume or multiple plumes beneath parga chasma we suggest that the concentration of volcanic features in the beta atla themis region may actually result from three independent but overlapping broad zones of deformation corona formation and enhanced volcanism associated with the three rifts parga hecate and devana chasmata rather than one large zone of activity covering the whole of the region simultaneously

spatial distribution and alignments of volcanic centers clues to the formation of monogenetic volcanic fields monogenetic basaltic volcanic fields occur worldwide in tectonic environments ranging from extensional to convergent understanding similarities and differences between these fields may help to characterize key controls on their generation such volcanic fields consist of numerous volcanic centers each of which represents a pathway of magma from its source to the surface we analyzed the spatial distribution of volcanic centers in 37 monogenetic volcanic fields and assuming that the distribution of volcanic centers relative to each other is matched by a similar source pattern within the mantle applied the following methods for each 1 the poisson nearest neighbor pnn analysis representing the degree to which the distribution of the volcanic centers departs from a predicted poisson distribution and 2 a volcanic alignment analysis to ascertain the preferential pathways if any used by the magma to reach the surface this is the first comprehensive global comparison of such analyses magma pathways within the brittle upper crust are influenced to various degrees by two end member situations 1 formation of new extension fractures perpendicular to the least compressive stress 3 and 2 re activation of pre existing fractures that are near parallel to the maximum principal stress 1 the results of the pnn analysis show that independently of the tectonic environment most volcanic fields display a clustered distribution of their volcanic centers alignment analysis shows that either the ambient tectonic environment exerts a strong influence on the preferential orientations of the volcanic alignments or that it is in competition with other factors e g pre existing structures local stress changes due to older intrusions overall these results indicate that the propagation of the magma and therefore the spatial distribution of the volcanic centers within volcanic fields is the product of an interplay between deep level influences i e nature of the magma source and shallow level influences i e stress field pre existing crustal structures of the lithosphere

slope stability probability classification waikato coal measures new zealand abstract ferm classified lithological units have been identified and described in the waikato coal measures in open pits in the waikato coal region these lithological units have been classified geotechnically by mechanical tests and discontinuity measurements using these measurements slope stability probability classifications sspc have been quantified based on an adaptation of hack s slope stability probability classification itc delft publication enschede netherlands vol 43 1998 273 pp sspc system which places less influence on rock quality designation and unconfined compressive strength than previous slope rock mass rating systems the hack weathering susceptibility rating has been modified by using chemical index of alteration values determined from xrf major element analyses slaking is an important parameter in slope stability in the waikato coal measures lithologies and hence a non subjective method of assessing slaking in relation to the chemical index of alteration has been introduced another major component of this adapted sspc system is the inclusion of rock moisture content effects on slope stability the main modifications of hack s sspc system are the introduction of rock intact strength derived from the modified mohr coulomb failure criterion which has been adapted for varying moisture content weathering state and confining pressure it is suggested that the subjectivity in assessing intact rock strength within broad bands in the initial sspc system is a major weakness of the initial system initial results indicate a close relationship between rock mass strength values calculated from rock mass friction angles and rock mass cohesion values derived from two established rock mass classification methods modified hoek brown failure criteria and mrmr and the adapted sspc system the advantage of the modified sspc system is that slope stability probabilities based on discontinuity independent and discontinuity dependent data and a maximum slope height are predicted the modified sspc system may be useful in predicting initial optimum pit slope designs in proposed greenfield mine sites xrf major element and chemical index of alteration cia results obtained for lithologies in the waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings this paper explains the systematic approach of using the adapted sspc system to classify slope stability in the waikato open pit coal mines

remote sensing evidence of lava ground ice interactions associated with the lost jim lava flow seward peninsula alaska thermokarst terrains develop when ice bearing permafrost melts and causes the overlying surface to subside or collapse this process occurs widely throughout arctic regions due to environmental and climatological factors but can also be induced by localized melting of ground ice by active lava flows the lost jim lava flow ljlf on the seward peninsula of alaska provides evidence of former lava ground ice interactions associated geomorphic features on the scale of meters to tens of meters were identified using satellite orthoimages and stereo derived digital terrain models the flow exhibits positive and mixed relief features including tumuli n 26 and shatter rings n 4 as well as negative relief features such as lava tube skylights n 100 and irregularly shaped topographic depressions n 1188 that are interpreted to include lava rise pits and lava induced thermokarst terrain along the margins of the flow there are also clusters of small peripheral pits that may be the products of meltwater or steam escape on mars we observed morphologically similar pits near lava flow margins in northeastern elysium planitia which suggests a common formation mechanism investigating the ljlf may therefore help to elucidate processes of lava ground ice interaction on both earth and mars

hydrovolcanic features on mars preliminary observations from the first mars year of hirise imaging abstract we provide an overview of features indicative of the interaction between water and lava and or magma on mars as seen by the high resolution imaging science experiment hirise camera during the primary science phase of the mars reconnaissance orbiter mro mission the ability to confidently resolve meter scale features from orbit has been extremely useful in the study of the most pristine examples in particular hirise has allowed the documentation of previously undescribed features associated with phreatovolcanic cones formed by the interaction of lava and groundwater on rapidly emplaced flood lavas these include moats and wakes that indicate that the lava crust was thin and mobile respectively jaeger w l keszthelyi l p mcewen a s dundas c m russel p s 2007 science 317 1709 1711 hirise has also discovered entablature style jointing in lavas that is indicative of water cooling milazzo m p keszthelyi l p jaeger w l rosiek m mattson s verba c beyer r a geissler p e mcewen a s and the hirise team 2009 geology 37 171 174 other observations strongly support the idea of extensive volcanic mudflows lahars evidence for other forms of hydrovolcanism including glaciovolcanic interactions is more equivocal this is largely because most older and high latitude terrains have been extensively modified masking any earlier 1 10 m scale features much like terrestrial fieldwork the prerequisite for making full use of hirise s capabilities is finding good outcrops