equilibrium disequilibrium and nonequilibrium landforms in the landscape abstract landscapes are composed of a diversity of landforms that may be characterized as equilibrium disequilibrium or nonequilibrium equilibrium is a constant relation between input and output or form toward which a landform tends or around which it fluctuates in time because of recent environmental changes and long relaxation times however many landforms are not adjusted to present inputs disequilibrium landforms are those that tend toward equilibrium but have not had sufficient time to reach such a condition some landforms called nonequilibrium do not tend toward equilibrium even with relatively long periods of environmental stability but rather undergo frequent and large change in form nonequilibrium may be caused by high magnitude thresholds that cause low frequency weather events to dominate form positive feedbacks and or nonlinearities that result in deterministic chaos landscapes contain mixtures of equilibrium disequilibrium and nonequilibrium landforms and these types of landforms interact in geomorphic systems such as sediment cascades the three types of behavior may coexist in the same landscape and the outputs of such mixed geomorphic systems reflect the combined effects of equilibrium disequilibrium and nonequilibrium subsystems this classification provides a framework for analysis and modeling of complex landscapes

planetary surface dating from crater size frequency distribution measurements partial resurfacing events and statistical age uncertainty abstract we describe the procedure to fit a cumulative production function polynomial to a partial crater size frequency distribution the technique is of particular use in deriving ages for surfaces which have undergone partial resurfacing events namely erosional or depositional events which have affected a limited diameter range of the crater population we demonstrate its use in obtaining times for both the surface formation and the resurfacing event we give a practical outline of the method for making age measurements from crater counts and how to identify resurfacing effects in the results we discuss the conversion of production function polynomials between common presentations and the statistical uncertainty of the determined ages with respect to the non linear chronology function and a minor refinement of data binning

chloride bearing materials in the southern highlands of mars chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing spectrally distinct surface deposits consistent with chloride bearing materials have been identified and mapped using data from the 2001 mars odyssey thermal emission imaging system these deposits are found throughout regions of low albedo in the southern highlands of mars geomorphologic evidence from orbiting imagery reveals these deposits to be light toned relative to their surroundings and to be polygonally fractured the deposits are small

effects of h2o ph and oxidation state on the stability of fe minerals on mars 1 on mars there is evidence that solutions may have been present on the surface episodically in the past these solutions were derived by weathering minerals such as olivine and sulfides found in mafic ultramafic rocks and possibly sulfates and meteorite fragments upon removal of water and or supersaturation of solutions secondary minerals formed we present a theoretical model for the formation of the solutions and the subsequent precipitation of fe bearing phases the first fe bearing phases to weather via oxidation are sulfides troilite or pyrrhotite which produce secondary fe hydr oxides or fes 2 pyrite or marcasite and fe 2 sulfates such as melanterite melanterite may be replaced by fe sulfates that have decreasing h 2 o 3fe 3 2fe 2 increasing oxidation and increasing bulk oh oh 2so 4 at meridiani planum the presence of jarosite indicates that the solutions were oxidized with ph 4 5 the solutions were likely fe mg ca s04 cl rich and precipitated fe hydr oxides fe phosphates fe sulfates with low oh oh so 4 ca mg sulfates and possible halides along with si rich phases the minerals indicating an acid environment were preserved by either removing components such as salts or water from the system e g in dust storms or episodic aqueous events isolating the mineral surfaces from fluids using disequilibrium processes or a combination at other localities jarosite is below detection limits and schwertmannite may be present if schwertmannite is present the solution had near neutral ph 4 ph 10 and fe hydr oxides would have crystallized rapidly leaving mg na ca s04 cl rich solutions that likely precipitated ca phosphates ca mg na sulfates fe sulfates with moderate high oh oh so 4 halides si rich phases and possibly fe mg ca carbonates

spectral and geological study of the sulfate rich region of west candor chasma mars sulfates have been discovered by the omega spectrometer in different locations of the planet mars they are strongly correlated to light toned layered deposits in the equatorial regions west candor chasma is the canyon with the thickest stack of layers and one with the largest area covered by sulfates a detailed study coupling mineralogy derived from omega spectral data and geology derived from hrsc imager and other datasets leads to some straightforward issues the monohydrated sulfate kieserite is found mainly over heavily eroded scarps of light toned material it likely corresponds to a mineral present in the initial rock formed either during formation and diagenesis of sediments or during hydrothermal alteration at depth because it is typically found on outcrops that are eroded and steep polyhydrated sulfates that match any ca na fe or mg sulfates with more than one water molecule are preferentially present on less eroded and darker outcrops than outcrops of kieserite these variations can be the result of a diversity in the composition and or of the rehydration of kieserite on surfaces with longer exposure the latter possibility of rehydration in the current or recent atmosphere suggests the low surface temperatures preserve sulfates from desiccation and also can rehydrate part of them strong signatures of iron oxides are present on sulfate rich scarps and at the base of layered deposits scarps they are correlated with tes gray hematite signature and might correspond to iron oxides present in the rock as sand size grains or possibly larger concretions that are eroded and transported down by gravity at the base of the scarp pyroxenes are present mainly on sand dunes in the low lying terrains pyroxene is strongly depleted or absent in the layered deposits when mixed with kieserite local observations favor a spatial mixing with dunes over layered deposits sulfates such as those detected in the studied area require the presence of liquid water to form by precipitation either in an intermittent lacustrine environment or by hydrothermal fluid circulation both possibilities require the presence of sulfur rich groundwater to explain fluid circulation the elevation of the uppermost sulfate signatures suggests the presence of aquifers up to 2 5 km above datum only 1 km below the plateau surface

evidence for weathering on early mars from a comparison with terrestrial weathering profiles abstract phyllosilicates on mars are widespread in the ancient crust suggesting the presence of liquid water at the martian surface and therefore warmer conditions during its early history however the role of the ancient climate in the alteration process which produced these phyllosilicates remains under debate because similar mineral assemblages can be produced by hydrothermal alteration at depth this paper focuses on the origin of coincident outcrops of fe mg bearing phyllosilicates and al bearing phyllosilicates which are observed in several regions of mars we performed a detailed mineralogical comparison between a section in nili fossae mars and a weathering profile located at murrin murrin western australia the murrin murrin profile is developed in archaean serpentinized peridotite massifs over a 40 m thick sequence it has three alteration zones the serpentine mineral saprolite is found at the bottom immediately overlain by fe mg bearing smectites and then al bearing phyllosilicates kaolinite mixed with iron hydroxides this example illustrates how al dominated minerals can derive from the alteration of initially al poor ultramafic rocks by the intense leaching of mg2 this mineralogical sequence is very similar to that detected locally in nili fossae by orbital spectroscopy by analogy we propose that the mineral assemblage detected on mars is the result of long term weathering and thus could be the best evidence of past weathering as a direct result of a climate significantly warmer than at present

a swarm of small shield volcanoes on syria planum mars this study focuses on the volcanism in syria planum located at the center of the tharsis bulge at an altitude of 6 to 8 km above mars datum syria planum was previously recognized as a center for the tectonic activity of tharsis but not as a major locus for volcanic activity despite its centrality over the bulge using high resolution images from the high resolution stereo camera on mars express combined with mars observer laser altimeter data we have characterized a volcanic system that reveals a number of very interesting aspects of mars volcanism we identified a swarm of tens of coalesced shallow volcanic edifices typically 10 30 km diameter 0 1 0 2 km high and with slopes around 0 5 these characteristics are similar to those of small shield volcanoes found in iceland in addition an intermediate sized volcano which is the source of lava flows that extend over 200 km is observed west of this shield swarm our study characterizes a previously unrecognized volcanic assemblage on mars which appears to be much more developed than was documented before in terms of morphology inferred origin and periodicity of eruption the estimated lava flux of the syria planum volcanoes is of the same order as the lava flux of tharsis montes these characteristics suggest that syria planum experienced a very specific style of volcanism which we dated to the hesperian period

context camera investigation on board the mars reconnaissance orbiter 1 the context camera ctx on the mars reconnaissance orbiter mro is a facility instrument i e government furnished equipment operated by a science team not responsible for design and fabrication designed built and operated by malin space science systems and the mro mars color imager team marci ctx will 1 provide context images for data acquired by other mro instruments 2 observe features of interest to nasa s mars exploration program e g candidate landing sites and 3 conduct a scientific investigation led by the marci team of geologic geomorphic and meteorological processes on mars ctx consists of a digital electronics assembly a 350 mm f 3 25 schmidt type telescope of catadioptric optical design with a 5 7 field of view providing a 30 km wide swath from 290 km altitude and a 5000 element ccd with a band pass of 500 700 nm and 7 m pixels giving 6 m pixel spatial resolution from mro s nearly circular nearly polar mapping orbit raw data are transferred to the mro spacecraft flight computer for processing e g data compression before transmission to earth the ground data system and operations are based on 9 years of mars global surveyor mars orbiter camera on orbit experience ctx has been allocated 12 of the total mro data return or about 3 terabits for the nominal mission this data volume would cover 9 of mars at 6 m pixel but overlapping images for stereo mosaics and observation of changes and meteorological events will reduce this area ctx acquired its first instrument checkout images of mars on 24 march 2006

controls on palagonitization versus pedogenic weathering of basaltic tephra evidence from the consolidation and geochemistry of the keanakako i ash member kilauea volcano 1 on the summit of kilauea volcano incipient palagonitization and consolidation of vitric tephras from the 90 of the carbon is mantle derived we hypothesize that the palagonitized zones may denote the location of fossil steam vents similar to active vents exposed along circumferential faults on both the north and the south sides of the kilauea caldera elsewhere keanakako i tephras are weathering into pedogenic products that closely reflect modern environmental conditions under acidic soil conditions ph 6 0 tephra is undergoing dissolution with the development of opaline crusts on outcrop faces under more neutral soil ph 6 5 7 8 the pedogenic products reflect the degree of desilication of tephra mitigated by leaching dominantly smectite where mean annual rainfall is 50 cm yr and dominantly kaolinite allophane and or imogolite where rainfall exceeds 250 cm yr

identification of carbonate rich outcrops on mars by the spirit rover decades of speculation about a warmer wetter mars climate in the planet s first billion years postulate a denser co2 rich atmosphere than at present such an atmosphere should have led to the formation of outcrops rich in carbonate minerals for which evidence has been sparse using the mars exploration rover spirit we have now identified outcrops rich in magnesium iron carbonate 16 to 34 weight percent in the columbia hills of gusev crater its composition approximates the average composition of the carbonate globules in martian meteorite alh 84001 the gusev carbonate probably precipitated from carbonate bearing solutions under hydrothermal conditions at near neutral ph in association with volcanic activity during the noachian era

an analysis of the earthquake time series at mount st helens washington in the framework of recent volcanic activity abstract the analysis of the earthquake time distribution at mount st helens reveals a good correlation between the physical state of the volcano and statistical parameters of earthquake sequence there are three main seismic phases in the whole 1980 1986 period the first one precedes the main eruption of may 18 1980 it begins with a sudden increase of the seismicity level in late march and continues with an utsu 1961 type decay of the seismic occurrence rate characterized by a small value of the decay coefficient the second phase lasts from the cataclysmic eruption on may 18 1980 until the continuous dome building episode in 1983 and is characterized by a very slow exponential increase of the background level of seismicity the third phase covers the remaining part of the sample and is characterized by a stationary earthquake clustering process episodically interrupted by peaks of activity related to eruptions the trends in seismic occurrence rate within each phase as well as the statistical parameter variations at each transition are analyzed and discussed in the framework of volcanic activity this leads to the conclusion that statistical techniques may give a significant contribution in understanding changes in volcanic processes such as those at mount st helens

overview of the spirit mars exploration rover mission to gusev crater landing site to backstay rock in the columbia hills spirit landed on the floor of gusev crater and conducted initial operations on soil covered rock strewn cratered plains underlain by olivine bearing basalts plains surface rocks are covered by wind blown dust and show evidence for surface enrichment of soluble species as vein and void filling materials and coatings the surface enrichment is the result of a minor amount of transport and deposition by aqueous processes layered granular deposits were discovered in the columbia hills with outcrops that tend to dip conformably with the topography the granular rocks are interpreted to be volcanic ash and or impact ejecta deposits that have been modified by aqueous fluids during and or after emplacement soils consist of basaltic deposits that are weakly cohesive relatively poorly sorted and covered by a veneer of wind blown dust the soils have been homogenized by wind transport over at least the several kilometer length scale traversed by the rover mobilization of soluble species has occurred within at least two soil deposits examined the presence of monolayers of coarse sand on wind blown bedforms together with even spacing of granule sized surface clasts suggests that some of the soil surfaces encountered by spirit have not been modified by wind for some time on the other hand dust deposits on the surface and rover deck have changed during the course of the mission detection of dust devils monitoring of the dust opacity and lower boundary layer and coordinated experiments with orbiters provided new insights into atmosphere surface dynamics

chronology eruption duration and atmospheric contribution of the martian volcano apollinaris patera geologic mapping thermal inertia measurements and an analysis of the color visual wavelengths of the martian volcano apollinaris patera indicate the existence of two different surface materials comprising an early easily eroded edifice and a more recent competent fan on the southern flank a chronology of six major events that is consistent with the present morphology of the volcano has been identified we propose that large scale explosive activity occurred during the formation of the main edifice and that the distinctive fan on the southern flank appears to have been formed by lavas of low eruptive rate similar to those that form compound pahoehoe flow fields on earth a basal escarpment typically 500 m in relief and morphologically similar to the one surrounding olympus mons was produced between the formation of the main edifice and the fan indicating multistage eruptions over a protracted period of time contact relations between the volcanic units and the adjacent chaotic material indicate that formation of the chaotic material occurred over an extended period of time and may be related to the volcanic activity that formed apollinaris patera stereophotogrammetric measurements permit the volume of the volcano to be estimated at 105 km3 from this volume measurement and an inferred eruption rate 1 5 10 2 km3 yr 1 we estimate the total eruption duration for the main edifice to be 107 yrs plausible estimates of the exsolved volatile content of the parent magma imply that greater than 1015 kg of water vapor was released into the atmosphere as a consequence of this activity this large amount of water vapor as well as other exsolved gases must have had a significant impact on local and possibly global climatic conditions

hydrated mineral stratigraphy of ius chasma valles marineris new high resolution spectral and morphologic imaging of deposits on walls and floor of ius chasma extend previous geomorphic mapping and permit a new interpretation of aqueous processes that occurred during the development of valles marineris we identify hydrated mineralogy based on visible near infrared vnir absorptions we map the extents of these units with crism spectral data as well as morphologies in ctx and hirise imagery three cross sections across ius chasma illustrate the interpreted mineral stratigraphy multiple episodes formed and transported hydrated minerals within ius chasma polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma they may have been precipitates in a closed basin or diagenetically altered after deposition fluvial or aeolian processes then deposited layered fe mg smectite and hydrated silicate on the chasma floor postdating the sulfates the smectite apparently was weathered out of noachian age wallrock and transported to the depositional sites the overlying hydrated silicate is interpreted to be an acid leached phyllosilicate transformed from the underlying smectite unit or a smectite jarosite mixture the finely layered smectite and massive hydrated silicate units have an erosional unconformity between them that marks a change in surface water chemistry landslides transported large blocks of wallrock some altered to contain fe mg smectite to the chasma floor after the last episode of normal faulting and subsequent landslides opal was transported short distances into the chasma from a few m thick light toned layer near the top of the wallrock by sapping channels in louros valles alternatively the material was transported into the chasma and then altered to opal the superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential distinct aqueous environments characterized by alkaline then circum neutral and finally very acidic surface or groundwater chemistry

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

halloysite as a kinetically controlled end product of arid zone basalt weathering abstract mineralogical and isotope results paired with field observations suggest that halloysite is the favored albeit metastable aluminosilicate end product of arid zone basalt weathering on kohala hawai i and that the formation of smectite has been inhibited by kinetic factors soils sampled on constructional lava flows having ages ranging from 4 to 350 ka provide a chronosequence that has had minimal physical disturbance thus allowing us to interpret chemical and mineralogical changes as the result of a time dependent process the halloysite content of the soil increases with increasing soil age its growth is at the expense of allophane which in turn forms at the expense of primary minerals these mineral relationships suggest that halloysite has been forming continuously throughout the lifetime of the soil smectite the thermodynamically stable phyllosilicate phase predicted by soil solution composition is not found in these arid soils we determined that our soil system is controlled by kinetic factors and that therefore thermodynamic predictions do not reflect reality the main factors favoring kinetic control of halloysite formation are intense but short wet periods followed by prolonged extremely dry seasons and microenvironmental conditions leading to immediate uptake of released al by the halloysite precursor mineral allophane the 18o relationship between present day soil water and halloysite formed over the last 170 ka was used as a tracer of past soil conditions results from a reconstruction of paleo climate and soil conditions combined with 18o data observed mineral relationships along the 350 ka chronosequence and field evidence for long term aridity rule out the possibility that the arid side of kohala was affected by prolonged periods of higher rainfall that could have produced more dilute soil waters and therefore altered mineralogical stabilities we conclude that pedogenic halloysite has been continually forming from the early stage of soil formation and that it has consistently formed under isotopic equilibrium conditions indicating that halloysite 18o compositions imply paleoclimatic conditions over the time of its formation that are similar to today s

mineralogy of juventae chasma sulfates in the light toned mounds mafic minerals in the bedrock and hydrated silica and hydroxylated ferric sulfate on the plateau 1 juventae chasma contains four light toned sulfate bearing mounds denoted here as a d from west to east inside the trough mafic outcrops at the base of the mounds and in the wall rock and light toned layered deposits of opal and ferric sulfates on the plateau hyperspectral visible near infrared compact reconnaissance imaging spectrometer for mars crism spectra were used to identify monohydrated and polyhydrated sulfate phs outcrops of layered material on the bright mounds most of the monohydrated sulfate signatures closely resemble those of szomolnokite feso4 h2o characterized by a water band near 2 08 m while some areas exhibit spectral features more similar to those of kieserite mgso4 h2o with a band centered closer to 2 13 m the largest phs outcrops occur on the top of mound b and their spectral features are most consistent with ferricopiapite melanterite and starkeyite but a specific mineral cannot be uniquely identified at this time coordinated analyses of crism maps mars orbiter laser altimeter elevations and high resolution imaging science experiment images suggest that mounds a and b may have formed together and then eroded into separate mounds while mounds c and d likely formed separately mafic minerals low ca pyroxene high ca pyroxene and olivine are observed in large 2 10 km wide outcrops in the wall rock and in smaller outcrops 50 500 m across at the floor of the canyon most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals the plateau region northwest of juventae chasma is characterized by an abundance of light toned layered deposits one region contains two spectrally unique phases exhibiting a highly stratified terraced pattern crism spectra of one unit eroded into swirling patterns with arc like ridges exhibit a narrow 2 23 m band assigned to hydroxylated ferric sulfate a thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate bearing light toned layered deposits hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units

mineralogy of recent volcanic plains in the tharsis region mars and implications for platy ridged flow composition volcanism on mars occurred until recently but the mineralogy of recent lava plains is poorly known because few regions display fresh outcrops devoid of dust using visible and near infrared data of the mars express probe two new volcanic plains in noctis labyrinthus have been identified and the existence of a volcanic plain on the floor of echus chasma has been confirmed crater retention ages estimated for these three plains range between 50 and 100 my corresponding to the late amazonian these plains represent an excellent opportunity to constrain the mineralogy of recent volcanic rocks results show that basaltic compositions with plagioclase and high calcium pyroxene are predominant the low olivine proportion suggests that the apparent fluidity of these flat plains is not related to magmas being ultramafic in addition a platy ridged texture is observed in two of the studied regions our study shows for the first time that this texture is associated with volcanic rocks and that these rocks are of typical basaltic mineralogy finally these volcanic plains are located more than 1000 km east of previously known late amazonian volcanic centers of the tharsis region an observation to be taken into account when considering models of recent volcanism on mars c 2009 elsevier bm all rights reserved

iron ore mining promotes iron enrichment in sediments of the gualaxo do norte river basin minas gerais state brazil the objective of the present study is to assess the influence of iron ore mining on fe concentrations in fluvial sediments of the gualaxo do norte river basin minas gerais state brazil initially background values were determined for fe by means of the boxplot representation the iterative 2 technique and the calculated distribution function using geochemical data obtained for alluvial terraces geochronologic analyses in carbonaceous materials attested for the proposed background values after that chemical analyses of active drainage sediments collected along the entire basin were carried out and a geochemical map of the study area was prepared the mean background value for fe is relatively high 8 2 wt when compared to the fe concentration in the earth s crust 5 6 wt such background value is strongly associated with the geological characteristics of the region it was observed that most of the high fe concentrations were detected in active sediments collected in the main river of the basin and not in its tributaries this suggests that fe enrichment is not only linked to the local geology but also to possible increase resulting from accidental leakage of iron ore mining tailings from containment dams and lakes upstream it is suggested that measures that help stop or minimize such impact be adopted the large capacity of fe to adsorb and form complexes with toxic metals implicates in environmental hazards that may not be restricted only to the gualaxo do norte river basin but may affect the other basins downstream

geological and geochemical legacy of a cold early mars 1 we consider the hypothesis that mars never experienced an early warm wet period and the implications of a continuously cold martian climate for the hydrology and geochemistry of the planet geomorphic evidence previously interpreted to indicate a more temperate early climate can be explained by cold climate processes and the transient flow of liquid water at the surface rather than a terrestrial like hydrological cycle in this scenario freezing and confinement of crustal aquifers lead to the eruption of water or brines to the surface hesperian events formed massive ice sheets and triggered floods that carved the outflow channels while smaller present day aqueous eruptions are responsible for the seepage and gully like landforms identified in high resolution imaging this process may have fluxed a significant volume of groundwater to the surface and the polar caps a primordial source of groundwater reconciles the present d h isotopic ratio of the atmosphere with fractionating atmospheric escape and a primordial martian d h inferred from hydrous phases of snc meteorites a cold early climate and a thin co2 atmosphere are consistent with the ubiquity of primary igneous minerals and the apparent absence of secondary minerals and copious carbonates on the surface aqueous eruptions introduced soluble chloride and sulfate salts into martian soils leaving clays and carbonates within the crust if the martian crust hosts a deep biosphere aqueous eruptions can bring organisms or their chemical signature to the surface the biotic component of any recent eruptions may be preserved in transient ice in cold traps on the surface

a late amazonian alteration layer related to local volcanism on mars hydrated minerals on mars are most commonly found in ancient terrains dating to the first billion years of the planet s evolution here we discuss the identification of a hydrated light toned rock unit present in one chasma of the noctis labyrinthus region stratigraphy and topography show that this alteration layer is part of a thin unit that drapes pre existing bedrock crism spectral data show that the unit contains hydrated minerals indicative of aqueous alteration potential minerals include sulfates such as bassanite caso4 1 2h2o or possibly hydrated chloride salts the proximity of a smooth volcanic plain and the similar crater model age late amazonian 100 myr of this plain and the draping deposits suggest that the alteration layer may be formed by the interaction of water with ash layers deposited during this geologically recent volcanic activity the alteration phases may have formed due to the presence of snow in contact with hot ash or eventually solid gas interactions due to the volcanic activity the relatively young age of the volcanic plain implies that recent alteration processes have occurred on mars in relation with volcanic activity but such local processes do not require conditions different than the current climate

topography of valley networks on mars from mars express high resolution stereo camera digital elevation models 1 martian valley networks have been identified mainly in the noachian heavily cratered uplands the geometry of valley networks can be studied using mars orbiter laser altimeter mola altimetry which is sufficient to map large valleys without a detailed 3 d shape of valley networks imaging from the mars express high resolution stereo camera hrsc is used to generate digital elevation models dems with resolution 50 m and vertical accuracy 60 m we studied valleys near huygens crater and in the aeolis region both in the noachian bedrock and on the west echus plateau in hesperian bedrock hrsc dems in these areas show that 1 drainage density is 3 times higher than is observed in mola data 2 degree of ramification is 1 order more than with mola 3 transverse valley profiles show a v shape more accurately and a minimum depth of 20 m and 4 higher drainage density shows greater headward extension that is not correlated to greater valley depth the deepest valleys 400 m are found in the huygens region where the density in the dem is 0 1 km 1 compared to shallow valleys 100 m of the echus region where the density is higher 0 3 km 1 these regional differences are due to spatially variable preservation and bedrock lithology longitudinal profiles suggest variations in duration of activity profile concavity is only developed in some noachian terrains valleys visible in hrsc images correspond to topographic features in dems showing the same geometry as terrestrial valleys thought to be formed by overland flows and seepage

mineralogical and geochemical indicators of the polygenetic nature of terra rossa in istria croatia abstract terra rossa in istria is situated on the jurassic cretaceous paleogene carbonate plain and is considered a polygenetic reddish soil which bears typical terra rossa fe oxide characteristics e g fe d and fe d fe t the difference in particle size mineralogy and geochemistry observed between terra rossa and the insoluble residue of limestones and dolomites clearly indicates that the additions of external materials might have diminished the influence of insoluble residue of limestones and dolomites as the primary parent material of terra rossa in istria terra rossa is clay and silty clay composed of quartz plagioclase k feldspar micaceous clay minerals illitic material and mica kaolinites kl d and kl chlorite vermiculite low charge vermiculite or high charge smectite mixed layer clay minerals other than illitic material hematite goethite and xrd amorphous inorganic compound calcite dolomite and boehmite are sporadically present and are of local importance kaolinites and illitic material are dominant clay mineral phases in the clay fraction of all terra rossa from istria kaolinite which does not form intercalation compounds with dimethylsulfoxide dmso is the dominant mineral phase in fine clay and is considered predominantly authigenic rather then inherited from parent materials neither the content and particle size distribution nor the bulk and clay mineralogy of the insoluble residue of limestone and dolomite support development of terra rossa entirely by dissolution of carbonate rock if terra rossa has developed only from the insoluble residue of limestone and dolomite its clay content due to weathering should be higher than that in the insoluble residues which is not the case plagioclase was found only in one insoluble residue while all terra rossa samples contain this mineral moreover insoluble residues do not contain vermiculite which was observed in small amounts in clay fraction of all terra rossa samples na 2 o k 2 o 100 zr nb and zr ti 1000 ratios in the majority of terra rossa samples are much higher than in the insoluble residue of limestones and dolomites which also supports external material influence in the genesis of terra rossa materials other than the insoluble residue of limestones and dolomites which might have contributed to terra rossa are loess sediments whose deposition was very important recurrent process in istria probably since the early middle pleistocene and flysch sediments which extended much more southwards from its present position analyses performed indicate that both loess older than that of the upper pleistocene age and flysch might have contributed in the genesis of terra rossa

mars surface diversity as revealed by the omega mars express observations the observatoire pour la mineralogie l eau les glaces et l activite omega investigation on board the european space agency mars express mission is mapping the surface composition of mars at a 0 3 to 5 kilometer resolution by means of visible near infrared hyperspectral reflectance imagery the data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy offering key insights into the evolution of mars omega has identified and mapped mafic iron bearing silicates of both the northern and southern crust localized concentrations of hydrated phyllosilicates and sulfates but no carbonates and ices and frosts with a water ice composition of the north polar perennial cap as for the south cap covered by a thin carbon dioxide ice veneer

mineralogical characterization of acid weathered phyllosilicates with implications for secondary martian deposits abstract the detection of phyllosilicates and sulfates on mars has revealed a complex aqueous history which suggests distinct geochemical environments separated temporally and spatially recent observations by mro crism in mawrth vallis have shown that phyllosilicate deposits exhibit a specific stratigraphy which remains incompletely understood moreover mer spirit has evidenced association between phyllosilicates amorphous silica and sulfates we investigated the hypothesis that these parageneses resulted from the acidic weathering of older phyllosilicate deposits we exposed nontronite fe rich smectite montmorillonite al rich smectite and kaolinite to h 2 so 4 solutions at ph 0 2 and 4 and at a temperature of 60 c after the acid treatment a combination of mineralogical techniques was used to assess the degree of alteration of the three phyllosilicate minerals xrf xrd and esem measurements show that nontronite was the most unstable when acid leached followed by montmorillonite and then kaolinite progressive acidic leaching of nontronite leads to alteration of the phyllosilicate to amorphous silica along with fe sulfate and anatase and the formation of an acidic al fe rich solution alteration of montmorillonite resulted in the formation of fe al ca and mg sulfates and a al rich leaching solution comparatively leaching of kaolinite resulted in the formation of al sulfates and a al rich solution as well with only slight alteration of the primary mineralogical features the effects of acid leaching of the phyllosilicates were also observed in nir reflectance spectra allowing a comparison with crism spectra from mawrth vallis based on our results we propose a new model where acid leaching of mixed phyllosilicate deposits leads to kaolinite overlaying montmorillonite which in turn caps fe mg smectites leaching of cations and subsequent evaporation leads to sulfate deposits as supported by geochemical modeling while amorphous silica remains as a residue depending on the intensity ph and length of exposure of acidic leaching our model can explain the stratigraphic distribution of phyllosilicates and the association of sulfates silica and smectites

diverse mineralogies in two troughs of noctis labyrinthus mars two troughs in noctis labyrinthus display a diversity of mineral assemblages rarely seen spatially collocated on mars minerals identified from mars reconnaissance orbiter data within the troughs include polyhydrated and monohydrated sulfates an al clay e g kaolinite or beidellite fe mg smectites hydrated silica and or opal and a leached clay or jarosite mixture with a doublet absorption between 2 2 and 2 3 m units both pre date and post date smaller pits and depressions within the larger troughs indicating that deposition was coeval with continued extension collapse and erosion in the late hesperian to early amazonian 2 3 ga the strata within each trough display a mineralogic diversity consistent with active aqueous processes and or changing chemical conditions over time perhaps due to hydrothermal alteration of volcanic ash influxes of groundwater from nearby tharsis volcanism fumarole activity and melting snow and or ice the superposition of younger fe mg smectites over sulfates al clays and hydrated silica and or opal in both troughs indicates that this region is unique relative to most other locations on mars where the opposite progression is observed and the fe mg smectites are noachian older than 3 6 ga in age consequently these troughs may have been habitable regions on mars at a time when drier conditions dominated the surface

signatures of divergence and self organization in soils and weathering profiles abstract complex system behaviors such as self organization are difficult to address in geology system evolution often cannot be directly observed and in geology models and theory must be reconciled with field evidence however self organization can be addressed within the historical interpretive paradigm by applying a measure of the degree of self organization of geologic features using standard interpretive methods to determine the nature of changes and determining whether those changes result in an increase or decrease in organization in this way stable non self organizing convergent development can be distinguished from unstable chaotic self organizing divergent development kolmogorov entropy k entropy was used as a measure of the self organization of soil profiles in eastern north carolina in general the profiles are low in k entropy indicating a generally high level of predictability and information in the vertical arrangement of pedogenetic horizons as a broad generality the study p

paleoclimate of mars as captured by the stratigraphic record in gale crater a kilometers thick sedimentary sequence in gale crater exhibits stratigraphic changes in lithology that are consistent with transitions in aqueous and climatic conditions purported to be global in scale the sequence is divided into two formations where the lower formation exhibits a net transition in mineralogy from clay sulfate to sulfate oxide assemblages and is separated from the overlying upper formation by an erosional unconformity superposition and crater counts suggest strata in the lower formation lie along the noachian hesperian time stratigraphic boundary whereas beds in the upper formation which lack signatures indicative of clay minerals or sulfates are thinner more regularly spaced and clearly younger the observed stratigraphic trends are consistent with the rocks at gale crater recording a global transition from a climate favorable to clay mineral formation to one more favorable to forming sulfates and other salts

morphometric properties of martian volcanoes 1 mars orbiter laser altimeter mola data have been used to construct digital elevation models dem of the martian volcanoes in order to determine height flank slope caldera depth and volumes summit elevations range from 21 1 km to 0 5 km and relief varies from 1 0 km to almost 22 km average flank slopes are in the range of 1 to 10 consistent with basaltic shield volcanism the very low slopes of highland patera are also consistent with pyroclastic volcanism minimum volumes range from 1012 to 1015 m3 estimates of the time required to build these volcanoes on the basis of long term terrestrial eruption rates range from hundreds of thousands to tens of millions of years

stratigraphy in the mawrth vallis region through omega hrsc color imagery and dtm abstract the mawrth vallis region contains an extensive at least 300 km 400 km and thick 300 m finely layered at meter scale clay rich unit detected by omega we use omega hrsc dtms derived from stereoscopic imagery hrsc color imagery and high resolution imagery such as moc ctx and hirise to characterize the geometry and the composition of the clay rich unit at the regional scale our results show that the clay bearing unit can be divided into sub units on the basis of differences in color and composition in false color visible imagery alternating white bluish and orange red colored units correspond to a compositional succession of respectively al and fe or mg phyllosilicate rich material geological cross sections are presented along the principal outcrops of the region in order to define the stratigraphy of these sub units this method shows that the dips of the sub units are frequently close to the slopes of the present topography except for scarps visible at the dichotomy boundary inside impact craters walls and outcrops inside mawrth vallis in addition to the al and fe or mg phyllosilicate rich sub units an altered surface is identified as the lower basement unit we propose two possible end member scenarios to explain the derived stratigraphy 1 alteration of volcaniclastic aeolian or aqueous layered deposits of various compositions by groundwater resulting in distinct altered rocks or 2 alteration coeval with the deposition of sediments under varying chemical conditions in wet pedodiagenetic environment

experimental epithermal alteration of synthetic los angeles meteorite implications for the origin of martian soils and identification of hydrothermal sites on mars 1 the dissolution behavior and secondary minerals generated by experimental alteration of a synthetic los angeles basaltic shergottite la were evaluated at epithermal 75 c conditions starting ph values of 1 1 and 3 6 and water rock ratios ranging from 100 to 2000 were studied using flow through and batch reactor experimental apparatus dissolution of plagioclase dominates effluent solution chemistry under all experimental conditions little mg is released to solution because nearly 100 of the mg in unaltered la is contained in pyroxene m1 sites which are relatively resistant to dissolution secondary minerals generated include siliceous residue amorphous sio2 lepidocrocite and ferrihydrite anhydrite alunogen rhomboclase ferrinatrite halite and unidentified ca and na sulfates the dominance of alteration products of plagioclase suggests that la type basalts have not contributed significantly to the martian soils the search for hydrothermal sites by remote sensing may be hampered by the general similarity of the alteration products found in the near surface epithermal environment to those thought to exist in martian soils sulfates iron oxyhydroxides amorphous silica however the unique chemical composition of secondary products formed by la alteration may make detection of recent hydrothermal alteration of evolved basaltic rocks more straightforward in addition alteration in terrestrial epithermal environments associated with mafic to intermediate volcanic rocks generally produces abundant sulfides and kaolinite two potentially unique mineral phases which might also indicate the presence of active or extinct hydrothermal systems

mineralogical and chemical composition of three tuffs from northern israel abstract the mineralogical and chemical composition of three types black yellow and red of tuffs from mt peres in northern israel that differ in terms of degree of weathering were determined in order to understand the weathering sequence under mediterranean or semi arid conditions the black tuff is very slightly weathered and contains 62 volcanic glass 15 primary minerals 12 titano magnetite 5 halloysite and 4 5 hydroxyapatite the yellow tuff considered to be the weathering product of the black tuff contains only 4 volcanic glass and 21 primary minerals 8 fe rich minerals 51 amorphous material identified as halloysite like allophane 15 halloysite and 5 hydroxyapatite a different mineralogical composition from that of red tuff indicates that this material was formed during a different eruption the red tuff consisted of 29 volcanic glass 26 primary minerals different from those of the black tuff 11 iron bearing minerals 10 halloysite 5 hydroxyapatite and 19 amorphous material the specific surface area and cation exchange capacity of the black red and yellow tuff 7 28 174 m2 g 1 and 107 285 601 mmolc kg 1 at ph 7 respectively were in accord with their amorphous material contents

clay mineral formation and transformation in rocks and soils three mechanisms for clay mineral formation inheritance neoformation and transformation operating in three geological environments weathering sedimentary and diagenetic hydrothermal yield nine possibilities for the origin of clay minerals in nature several of these possibilities are discussed in terms of the rock cycle the mineralogy of clays neoformed in the weathering environment is a function of solution chemistry with the most dilute solutions favouring formation of the least soluble clays after erosion and transportation these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size clays undergo little reaction in the ocean except for ion exchange and the neoformation of smectite therefore most clays found on the ocean floor are inherited from adjacent continents upon burial and heating however dioctahedral smectite reacts in the diagenetic environment to yield mixed layer illite smectite and finally illite with uplift and weathering the cycle begins again

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

equilibrium scale and inheritance in geomorphology abstract of the many equilibrium terms that have been proposed only two are needed dynamic equilibrium in the original sense of g k gilbert 1877 and steady state the former refers to the relationship between the process components of a system the latter to the system as a whole the tendency towards establishing a dynamic equilibrium is inherent in all natural systems that contain negative feedbacks between processes capable of compensating each other in geomorphology equilibrium tendencies of the mass budget are more relevant than those of the energy budget the validity of the equilibrium concept is discussed at several scales from a slope point to entire slopes drainage basins and mountain ranges the effects of eksystemic changes vary depending upon the length of the intervals between such changes in comparison to the length of the required relaxation times this relationship also applies to the influence of inherited forms patterns and materials that have become components of present day systems

geochemical background in soils a linear process domain an example from istria croatia definition of geochemical background in exploration and environmental geochemistry has always been regarded as contingent upon scale and investigated locality but mostly under assumption that hosts of processes that produce the data more or less conform individually to gaussian law of central tendencies recently understanding of pedogenesis as synergetic process being characterized by non linear dynamics renders thermodynamic approach directly applicable in assessment of geochemical thresholds with concepts of linearity and normality set alongside in solving the problems of soil geochemistry seen from this perspective the work is an attempt to relate conceptual fundamentals of non linear dynamical theory to basic statistical methods in order to elucidate the nature and origins of element subpopulations hidden in the original geochemical data from the soils of istrian peninsula western croatia to this purpose the two major groups of soils were selected for analysis depending on the type of bedrock as one of the main soil forming factors geochemical data were subjected to the trimming procedure by which the outliers were removed from the total data collective and attributed to non linear causes precluding simple cause and effect relationships as the sine qua non of gaussian distribution geochemical background is then defined as the normal range of data of the remaining trimmed dataset indicating the thermodynamic branch of the specific soil processes as opposed to outliers being described as dissipative structures

in situ and experimental evidence for acidic weathering of rocks and soils on mars experimental data for alteration of synthetic martian basalts at ph 0 1 indicate that chemical fractionations at low ph are vastly different from those observed during terrestrial weathering rock surface analyses from gusev crater are well described by the relationships apparent from low ph experimental alteration data a model for rock surface alteration is developed which indicates that a leached alteration zone is present on rock surfaces at gusev this zone is not chemically fractionated to a large degree from the underlying rock interior indicating that the rock surface alteration process has occurred at low water to rock ratio the geochemistry of natural rock surfaces analyzed by apxs is consistent with a mixture between adhering soil dust and the leached alteration zone the chemistry of rock surfaces analyzed after brushing with the rat is largely representative of the leached alteration zone the chemistry of rock surfaces analyzed after grinding with the rat is largely representative of the interior of the rock relatively unaffected by the alteration process occurring at the rock surface elemental measurements from the spirit opportunity pathfinder and viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low ph low water to rock ratio alteration relationships developed for gusev rocks soils are affected principally by mobility of fe and mg consistent with alteration of olivine bearing basalt and subsequent precipitation of fe and mg bearing secondary minerals as the primary control on soil geochemistry copyright 2006 by the american geophysical union

sulfates and iron oxides in ophir chasma mars based on omega and crism observations abstract we investigate the sulfate and iron oxide deposits in ophir chasma mars based on short wave infrared data from the compact reconnaissance imaging spectrometer for mars crism and from the observatoire pour la mineralogie l eau les glaces et l activite omega sulfates are detected mainly in two locations in the valley between ophir mensa and the southern wall of ophir chasma kieserite is found both within the slope of ophir mensa and superposed on the basaltic wall of the chasm here kieserite is unconformably overlain by polyhydrated sulfate deposits and iron oxides locally jarosite and unidentified phases with absorptions at 2 21 m or 2 23 m are detected which could be mixtures of jarosite and amorphous silica or other poorly crystalline phases the second large sulfate rich outcrop is found on the floor of the central valley although the same minerals are found here polyhydrated sulfates kieserite iron oxides and locally a possibly jarosite bearing phase this deposit is very distinct it is not layered almost horizontal and located at a much lower elevation of below 4250 m kieserite superposes polyhydrated sulfate rich deposits and iron oxides form lags the facies of sulfate formation remains unclear and could be different for the two locations a formation in a lake playa or under a glacier is consistent with the mineralogy of the central valley and its flat low lying topography this is not conceivable for the kieserite deposits observed south of ophir mensa these deposits are observed over several thousands of meters of elevation which would require a standing body of water several thousands of meters deep this would have lead to much more pervasive sulfate deposits than observed these deposits are therefore more consistent with evaporation of groundwater infiltrating into previously sulfate free light toned deposits the overlying polyhydrated sulfates and other mineral phases are observed in outcrops on ridges along the slopes of the southern chasm wall which are too exposed to be reached by groundwater here a water supply from the atmosphere by rain snow fog or frost is more conceivable

tectonic history of the syria planum province of mars we attribute most of the development of extensive fractures in the tharsis region to discrete tectonic provinces within the region rather than to tharsis as a single entity one of these provinces is in syria planum faults and collapse structures in the syria planum tectonic province on mars are grouped into 13 sets based on relative age areal distribution and morphology according to superposition and fault crosscutting relations and crater counts we designate six distinct episodes of tectonic activity in the following chronologic order stage i is an early to late noachian deformation forming mostly east west structures fault set ia some large volcanoes also formed faults were produced possibly by flexural uplift also arcuate north trending grabens set ib indicate that faulting is transitional to the next stage stage ii is late noachian to early hesperian radial faulting centered in syria planum possibly due to isostatic uplift in late noachian set iia to early hesperian set iib time stage iii is early to late hesperian faulting tangential to syria planum that was related to local centers of uplift sets iii1 iii3 on the periphery of syria planum stage iv is a late hesperian graben formation that was circumferential to syria planum set iva caused either by collapse associated with eruption of magma or by flexure of the lithosphere due to volcanic loading in association with volcanism minor faulting occurred producing an oval pattern of faults in southwest syria planum set ivbl and a radial pattern south of the planum set ivb2 that apparently rejuvenated buried stage ii faults stage v is a late hesperian to early amazonian development of grabens and troughs of noctis labyrinthus and western valles marineris set v that was probably instigated by local uplift exposure of groundwater or ground ice zones may have produced further collapse and trough enlargement stage vi is early amazonian northwest trending faulting in noctis fossae set vil perhaps due to tharsis monies centered tectonism and north northwest normal faulting along the eastern side of the claritas rise set vi2 that was due to tectonic subsidence the duration of tectonic activity in the syria planum province was perhaps 2 3 b y photoclinometric topographic profiles across 132 grabens and fault scarps show that syria planum grabens have widths average of 2 5 km and most range from 1 to 6 km similar to lunar grabens but the martian grabens have slightly higher side walls average about 132 m and gentler wall slopes average of 9 and range of 2 25 than lunar grabens 93 m high and 18 slopes scarp degradation on mars has progressed through quakes impact shaking and dry slope processes the lower slopes may be due to mars higher gravity estimates of the amount of extension for individual grabens range from 20 to 350 m most estimates of the thickness of the faulted layer range from 0 5 to 4 5 km average is 1 5 km this thickness range corresponds closely to the 0 8 to 3 6 km range in depth for pits troughs and canyons in noctis labyrinthus and along the walls of valles marineris we propose that the predominant 1 to 1 5 km values obtained for both the thickness of the faulted layer and the depths of the pits troughs and theater heads of the canyons reflect the initial depth to the water table in this region as governed by the depth to the base of ground ice maximum depths for these features may indicate lowered groundwater table depths and the base of ejecta material

formation of glaciers on mars by atmospheric precipitation at high obliquity surface conditions on mars are currently cold and dry with water ice unstable on the surface except near the poles however geologically recent glacierlike landforms have been identified in the tropics and the midlatitudes of mars the ice has been proposed to originate from either a subsurface reservoir or the atmosphere we present high resolution climate simulations performed with a model designed to simulate the present day mars water cycle but assuming a 45 obliquity as experienced by mars a few million years ago the model predicts ice accumulation in regions where glacier landforms are observed on the western flanks of the great volcanoes and in the eastern hellas region this agreement points to an atmospheric origin for the ice and reveals how precipitation could have formed glaciers on mars

nonlinear dynamical systems in geomorphology revolution or evolution abstract geomorphic systems typically exhibit complex apparently random behaviors and patterns in both spatial and temporal domains this complexity can arise from the cumulative impacts of individual process response mechanisms which are far too numerous to be accounted for in individual detail or due to multiple controls over process response relationships which operate over a range of spatial and temporal scales stochastic complexity nonlinear dynamical systems nds theory which includes specific techniques and concepts such as chaos dissipative structures bifurcation and catastrophe theory and fractals shows that extreme complexity can also arise due to the nonlinear dynamics and couplings of relatively simple systems represented by relatively small equation systems deterministic complexity while emphasis in earth science has been largely on stochastic complexity geomorphologists have long recognized the presence of deterministic complexity as well recent developments in the study of nonlinear dynamical systems have implications for the ability to make reliable long term predictions and therefore applications of nds in geomorphology may be revolutionary to some extent however virtually all the basic conceptual underpinnings of nds theory can be mapped onto existing and even traditional theoretical concepts in geomorphology in this sense the use of nds concepts in understanding earth surface processes and landforms is evolutionary the link between traditional and nds based concepts is illustrated by analyzing a generalized geomorphic mass flux system it is shown that the system is in most cases unstable consistent with chaos or deterministic complexity however the three attractor states of the system correspond exactly to the states of aggradation degradation and steady state

most mars minerals in a nutshell various alteration phases formed in a single environment in noctis labyrinthus 1 a closed depression in the noctis labyrinthus region of mars at 10 4 s 98 6 w believed to have formed in the late hesperian holds an inner pit partially filled with several hundred meters of stratified material compact reconnaissance imaging spectrometer for mars crism visible near infrared reflectance data reveal signatures of numerous hydrated minerals including halloysite kaolinite fe smectite si oh bearing phases and fe sulfates polyhydrated monohydrated and hydroxylated types including jarosite we use crism data high resolution imagery hirise and hrsc high resolution stereo camera derived elevation to analyze the morphology composition and stratigraphy of these materials we propose an alteration sequence including formation of acid sulfate solutions from groundwater and magmatic sulfur which then locally altered the basaltic bedrock and layered sediments mainly deposited from volcanic tephra forming fe smectite and fe sulfates the mineral variability can mostly be explained by local variations in the ph of the altering fluids with original acidity being buffered by dissolution of primary minerals and by variable fluid input and evaporation and or freezing rates resulting in various water rock ratios this site shows local formation of almost all classes of minerals identified thus far on mars without invoking global conditions processes related to local volcanic activity and associated hydrothermalism were able to produce during an era in which the climate is believed to have been cold a large variety of hydrated minerals this study highlights the importance of the geological setting of hydrated minerals in the understanding of mars geologic and climatic evolution

geochemistry of istrian lower palaeogene bauxites is it relevant to the extent of subaerial exposure during cretaceous times abstract investigation of the origin and occurrence of istrian lower palaeogene bauxites discussed in this work relies on adoption of the recent perspectives on development of the collision induced diachronous discontinuity surface in the istrian part of the adriatic dinaric carbonate platform this process related to the forebulge uplift at the latest stages of alpine orogenesis is amply recorded in the geochemical signature of contemporaneous bauxites in order to elucidate the patterns of bauxite formation a discriminant function model based on the compositional data analysis major and trace elements is constructed providing the solid ground for separation of the bauxite groups deposited in the subaerially exposed istrian palaeoenvironment complete distinction between the four a priori defined istrian lower palaeogene bauxite groups achieved by the analysis demonstrates the highest degree of efficiency in characterizing environmental conditions marked by the unique suite of geochemical variables compositions

progressive and regressive pedogenesis and complex soil evolution abstract the simultaneous operation of regressive and progressive pedogenetic pathways raises the possibility that soil evolution may exhibit patterns far richer and more complex than increasing development over time this possibility is explored via a numerical model incorporating the relative rates of progressive and regressive pedogenesis and feedbacks between these rates and the degree of soil development this model may exhibit deterministic chaos and sensitive dependence on initial conditions with realistic parameter values variations in profile development in a region of the north carolina coastal plain where soil forming factors are relatively constant is consistent with deterministic chaos chaotic soil evolution suggests that soil development may reflect the interplay between progressive and regressive soil forming processes in addition to or instead of the age of a surface or deposit the former may produce a state of development which is unique to a particular time sensitively dependent on the unknown initial conditions and not simply related to age soils and their genetic signatures as indicators of relative ages and quaternary environments may need to be reinterpreted in this light

nonlinear dynamics and the evolution of relief abstract theories of landscape evolution and available field evidence suggest that topographic relief may increase decrease or remain relatively constant over time the trend depends on the relative balance between endogenic and exogenic forces and or the spatial scale a straightforward mathematical argument shows that when relief generally decreases over time or remains constant landscape evolution is stable and non chaotic chaotic unstable topographic evolution produces divergence where initial elevation differences and subsequent perturbations generally increase over time this leads to or at least towards a conceptual model of landscape evolution this model based on nonlinear dynamical systems nds theory recognizes 10 modes five stable and five chaotic of topographic evolution together these modes can accommodate existing theories and models of landscape evolution no mode can persist indefinitely over geologic time implying that landscapes inevitably undergo phases of increasing and decreasing relief these phases may be quite long because the model can accommodate any observed trend in relief evolution it is not falsifiable and is therefore not proposed as a theory the nds model does have implications with respect to the preservation of planar surfaces the next step is to develop a testable hypothesis