aerobic and anaerobic methane oxidation in terrestrial mud volcanoes in the northern apennines abstract methane oxidizing prokaryotes are ubiquitous in oxic and anoxic habitats wherever c1 compounds are present thus methane saturated mud volcano fluids should be a preferred habitat of methane consuming prokaryotes using the readily available electron donors in order to understand the relevance of methane as a carbon and energy source in mud volcano communities we investigate the diversity of prokaryotic organisms involved in oxidation of methane in fluid samples from the salse di nirano mud volcano field situated in the northern apennines cell counts were at approximately 0 7 106 microbial cells ml a fraction of the microbial biomass was identified as anme an aerobic me thanotroph archaea by fluorescence in situ hybridization fish analysis they are associated in densely colonized flakes of some tens of m in diameter embedded in a hyaline matrix diversity analysis based on the 16s rdna genes retrieved from amplified and cloned environmental dna revealed a high proportion of archaea involved in anaerobic oxidation of methane aom aerobic methane oxidizing proteobacteria could be highly enriched from mud volcano fluids indicating the presence of aerobic methanotrophic bacteria which may contribute to methane oxidation whenever oxygen is readily available the results imply that biofilms dominated by anme archaea colonize parts of the mud volcano venting system

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

the nature and hydrogeologic significance of mud diapirs and diatremes for accretionary systems in accretionary wedges often morphologically similar sedimentary intrusions when observed by remote geophysical means may have one of two quite different driving mechanisms and a highly variable significance for the regional hydrogeologic picture for example mud diapirs are driven by buoyancy forces that arise from bulk density contrasts in them mud and pore fluid upwell en masse and fluid migration is a related sometimes important but generally subsidiary process in contrast diatremes contain sediments fluidized during rapid fluid advection and are forcibly and directly driven by the hydrogeologic system the nature of fluid input from local and exotic source regions can therefore strongly affect sedimentary intrusive processes and vice versa this complicates the process of defining the main features of the hydrogeological systems operating in accretionary wedges focused vertical advection through steep sided piercement mud diapirs requires conduit systems otherwise flow will be diffuse and directed more horizontally out of the low permeability mud mass however where the permeability of the overburden is less than that of the diapir the whole diapir may act as a conduit apart from this special case conduits will be associated with highly anisotropic scaly fabrics that can sometimes develop in the marginal shear zone of diapirs scaly fabrics form during deformation and compaction of a mud matrix under conditions of constant or increasing effective stress however the effective stress path can be complex as it is both controlled by the relative rates of upward intrusion and burial by sedimentation and or structural thickening and the hydrogeologic system due to this it appears likely that even in a geographically related group of diapirs effective stress histories will vary widely between intrusions so that some can form advective pathways for fluids and some cannot mixed systems of behavior may also be present with local diatremes developing within diapirs above the terminations of conduit systems and rapidly expanding methane gas pockets the potentially heterogeneous near surface behavior may be why the surface manifestations of sedimentary intrusions are so variable when observed in the field diatremes can also form separately as large primary features above any structural or stratigraphic conduit that rapidly expels water or gas into the base of an unlithified sediment column when active large diatremes require enormous quantities of fluid water or gas to drive them particularly if they are long lived features and hence are a direct indication of at least an episodically vigorous hydrogeologic system

a genetic model of hydrocarbon derived carbonate chimneys in shelfal fine grained sediments the enza river field northern apennines italy abstract methane derived authigenic carbonate mdac concretions have been recently exposed in the pleistocene argille azzurre fm outcropping along the enza riverbanks northern apennines foothills italy the relations between the sediment deposition the coeval tectonic deformation and the mdac concretions have been investigated to unravel the mechanism of methane migration through the sediments and the processes leading to mdac occurrence the biogenic methane responsible for the formation of mdac chimneys and slabs has been generated in the organic rich pliocene sediments located in the po plain subsurface the gas migrated up dip towards the northern apennines foothills the mdac cements are mainly composed of dolomite whose precipitation requires thousand years and the absence of so 4 in the pore fluids according with the sedimentation rates of the mdac hosting pleistocene succession the sulphate methane transition zone migrated upwards faster than time required for dolomite precipitation therefore the connate water migrating together with the methane could have acted as second dic source allowing the mdac formation also in the methane rich zone

influence of topography on coseismic displacements induced by the friuli 1976 and the irpinia 1980 earthquakes italy analyzed through a two dimensional hybrid model 1 we investigate the perturbations introduced by the local topography on the coseismic displacement components induced by crustal seismic faults the approach proposed by tinti and armigliato 2002 is applicable to homogeneous two dimensional domains with arbitrary topography of the free surface it uses both analytical results valid for homogeneous spaces and half spaces bounded by a flat free surface ffs and a numerical code solving the equations of equilibrium of linear elasticity through a finite element fe scheme a major characteristic of our hybrid method is that it allows for the correct representation of the displacement components in correspondence with the fault which does not need to be explicitly introduced in the fe mesh we show that in the case of homogeneous domains this makes our approach preferable to pure fe schemes our hybrid approach is here applied to two different disastrous events of the recent italian seismic history for which topography is expected to play an important role namely the 6 may 1976 ms 6 5 friuli and the 23 november 1980 ms 6 9 irpinia basilicata earthquakes for each event we selected hypotheses for the parent fault proposed in the literature and compared the coseismic displacements computed through the widely used analytical models dealing with ffs and through our hybrid approach accounting for the effect of realistic topographies the most relevant effects are observed in the case of the irpinia earthquake depending on the profile chosen the computed misfits can be as high as 19 and 13 for the horizontal and vertical displacements respectively with absolute differences up to 9 and 10 cm

structural boron as factor controlling illite crystallinity in a mud volcano environment northern apennine italy abstract mud extrusion is a well known phenomenon whereby fluid rich fine grained sediments ascend within a lithological succession due to their buoyancy in this study of the terrestrial mud volcanism associated to an active thrusted area in the northern apennines we investigated the effect of boron incorporation in illite crystalline lattice a significant variation was recorded on the investigated mud samples with respect to both the amount of fixed boron 118 529 g g and the full width at half maximum height value fwhm of illite 0 29 0 62 2 we attribute these variations to the interaction between boron rich formation waters and the silty clayey lithologies of the local sedimentary succession the lack of any geographical correlation between the selected geochemical and mineralogical parameters is likely due to intensive thrust and fold deformation of the study area comparison of fwhm values with those from dellisanti et al 2008 santerno succession northern apennine lead us to suggest that application of fwhm as a depth indicator could be misleading within b rich hydro geological environments

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

impact of topography on earthquake static slip estimates abstract our understanding of earthquakes is limited by our knowledge and our description of the physics of the earth when solving for subsurface fault slip it is common practice to assume minimum complexity for characteristics such as topography fault geometry and elastic properties these characteristics are rarely accounted for because our knowledge of them is often partial and they can be difficult to include in simulations however topography and bathymetry are known all over the earth s surface and recently developed software packages such as specfem x have simplified the process of including them in calculations here we explore the impact of topography on static slip estimates we also investigate whether the influence of topography can be accounted for with a zeroth order correction which accounts for variations in distance between subfaults and the surface of the domain to this end we analyze the 2015 mw 7 5 gorkha nepal and the 2010 mw 8 8 maule chile earthquakes within a bayesian framework the regions affected by these events represent different types of topography chile which contains both a deep trench and a major orogen the andes has a greater overall elevation range and steeper gradients than nepal where the primary topographic feature is the himalayan mountain range additionally the slip of the continental nepal event is well constrained whereas observations are less informative in a subduction context we show that topography has a non negligible impact on inferred slip models our results suggest that the effect of topography on slip estimates increases with limited observational constraints and high elevation gradients in particular we find that accounting for topography improves slip estimates where topographic gradients are large when topography has a significant impact on slip the zeroth order correction is not sufficient

lipid biomarkers and their specific carbon isotopic compositions of cold seep carbonates from the south china sea abstract cold seep carbonates were studied from two locations dongsha and chiasian in the northern south china sea and on taiwan island lipid biomarkers and their stable carbon isotopic compositions extracted from these seep carbonate samples were analyzed in this study and the results pointed at the anaerobic oxidation of methane aom as responsible for carbonate formation distinct aom communities were indicated by isotopically highly depleted archaeal biomarkers with 13c values as low as 140 8 vpdb and bacterial biomarkers with 13c values as low as 128 6 vpdb which confirmed that biogenic methane was the dominant carbon source lipid biomarker distributions indicated that anme 2 archaea were prevalent in sample tvg3 c2g from dongsha and sample jx8 from chiasian in addition differences of the aom communities between the carbonates appeared to be caused by the respective biogeochemical environments anme 1 archaea tended to be abundant in high mg calcite carbonates and their formation might be linked to low methane fluxes in contrast anme 2 consortia were prevalent in aragonite carbonates and appeared to have prospered at sites with high methane supply our data imply that the mineralogy of the seep carbonates precipitated in the northern south china sea appears to be influenced by the distinct anme consortia which are induced by methane flux

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

in situ fluxes and zonation of microbial activity in surface sediments of the hakon mosby mud volcano from the hakon mosby mud volcano hmmv on the southwest barents sea shelf gas and fluids are expelled by active mud volcanism we studied the mass transfer phenomena and microbial conversions in the surface layers using in situ microsensor measurements and on retrieved cores the hmmv consists of three concentric habitats a central area with gray mud a surrounding area covered by white mats of big sulfide oxidizing filamentous bacteria beggiatoa and a peripheral area colonized by symbiontic tube worms pogonophora a fourth habitat comprised gray microbial mats near gas seeps the differences between these four methane fueled habitats are best explained by different transport rates of sulfate into the sediments and pore water upflow rates the upflow velocities were estimated by two independent methods at 3 6 m yr21 in the central area and 0 3 1 m yr21 in beggiatoa mats in the central area no sulfide was found indicating that the rapidly rising sulfate free fluids caused sulfate limitation that inhibited anaerobic oxidation of methane aom under beggiatoa mats a steep sulfide peak was found at 2 to 3 cm below the seafloor bsf most likely due to aom all sulfide was oxidized anaerobically possibly through nitrate reduction by beggiatoa the beggiatoa mats were dominated by a single filamentous morphotype with a diameter of 10 mm and abundant sulfur inclusions a high diversity of sulfide oxidizer morphotypes was observed in a grayish microbial mat near gas vents where aerobic sulfide oxidation was important the sediments colonized by pogonophora were influenced by bioventilation allowing sulfate penetration and aom to 70 cm bsf the hmmv is a unique and diverse ecosystem the structure and functioning of which is mainly controlled by pore water flow

effect of near fault terrain upon dislocation modeling coseismic surface deformation provides important information needed to determine source rupture geometry and slip distribution as well as to estimate seismic moment in this study numerical experiments were designed to analyze and classify how free surface topography affects surface deformation the investigation was performed by 3 d finite element modeling results of this study show that crustal deformation induced by near fault terrain is significant and can be measured with present geodetic survey techniques the characteristics of the terrain effects show that a hill structure produces more crustal deformation than a half space model and that the crustal deformation of a basin structure is less than that of the half space model the topographic correction is in the order of five percent of the fault dislocation on the basis of the relationship between fault offset and earthquake magnitude it is suggested that the terrain effects on the coseismic crustal deformation of shallow earthquakes with a magnitude greater than 5 6 should be considered as one of the major errors in coseismic deformation modeling which ignored the surface topography on the order of 300 meters

mud volcanoes the most important pathway for degassing deeply buried sediments abstract this paper discusses the nature of the phenomenon of mud volcanism with respect to degassing of deeply buried sediments mud volcanoes are defined as geological structures and their main elements are described based on the nature of activity mud volcanoes are grouped in to three main types and the relationship between each type and corresponding morphological expression is discussed the presented up to date data of the world geographical distribution of mud volcanoes show that they approximate to 1800 individuals a detail overview of geological environments in which they occur helps to deduce some necessary conditions for mud volcano formation the basic mechanisms of mud volcano formation are discussed specifically the fluid pressure hypothesis and some triggering events are identified the most common investigation approach and some criteria for recognizing of a submarine mud volcano on side scan sonar records and seismic sections are given mud volcanism in the mediterranean ridge an accretionary complex and black sea abyssal plane a back ark basin with tectonic regime of extension are described as case studies to show variety in morphology and common factors in development of mud volcanoes the manifestation of continuous gas migration through mud volcanoes is clarified and the attempt made to quantify the gas release shows that mud volcanoes are one of the significant natural sources of atmospheric methane emitting a total amount of about 10 3 to 12 6 tg annually

significance of mud volcanism 1 mud volcanism and diapirism have puzzled geoscientists for 2 centuries they have been described onshore and offshore in many places on earth and although they occur in various tectonic settings the majority of the features known to date are located in compressional tectonic scenarios this paper summarizes the main thrusts in mud volcano research as well as the various regions in which mud volcanism has been described mud volcanoes show variable geometry up to tens of kilometers in diameter and several hundred meters in height and a great diversity regarding the origin of the fluid and solid phases gas predominantly methane water and mud may be mobilized at subbottom depth of only a few meters but in places can originate from several kilometers depth with minor crustal or mantle input the possible contribution of mud extrusion to global budgets both from quiescent fluid emission and from the extrusive processes themselves is important in regions where mud volcanoes are abundant such as the collision zones between africa and eurasia fluid flux through mud extrusion exceeds the compaction driven pore fluid expulsion of the accretionary wedge also quiescent degassing of mud volcanoes may contribute significantly to volatile budgets and hence to greenhouse climate

sediment routing analyses based on chronological changes in hillslope and riverbed morphologies recent studies of sediment delivery and budgets in the united states indicate that upland erosion rates at a given time may not explain contemporaneous sediment yields from a drainage basin this suggests temporal discontinuities in sediment delivery associated with hillslope and channel storage processes integration of sediment production storage and transport is essential to understand sediment routing in basins we analysed each process chronologically using aerial photographs monitoring data of sediment movement and annual tree rings and then compared estimated temporal changes in sediment production from hillslopes floodplain disturbance areas and sediment transport in river channels toeslopes floodplains and alluvial fans together contained 59 per cent of sediment eroded from uplands over the last 30 years monitoring results of riverbed changes showed that the volume of stored sediment on floodplains decreased exponentially with succeeding floods the age distribution of floodplain deposits reflected the disturbance history of a river channel and followed an exponential decrease with age the results of this study may have important implications for sediment control plans for watersheds in steep regions

introduction to the special issue signatures of microbes and microbial mats and the sedimentary record abstract the present special issue originated from a session ssp4 5 at the egu general assembly 2010 vienna microbes and microbial mat signatures and the sedimentary record this special issue comprises a set of papers that focus on several aspects of microbial and microbial mat signatures grouped into four major fields 1 microbial biomineralisation 2 microbial communities and mat related structures 3 organo sedimentary accretion and microbial deposits and 4 processes and products in submarine cold seeps and terrestrial mud volcanoes

interrelations of mud volcanism fluid venting and thrust anticline folding examples from the external northern apennines emilia romagna italy 1 the present work aims to provide an example of connection between fluid seepage and fault fracture zones associated with compressional thrust folds surface fluid seepage along the pede apennine margin consists of mud volcanism and methane rich emissions showing an intimate link with thrust related folds dominant gaseous or ch4 bearing fluid emissions characterize thrust fold settings in which fluid escape from the main reservoir and source rock i e the marnoso arenacea flysch is not impeded by a seal layer conversely remarkable mud volcanism is closely linked to the presence of the impermeable ligurian units sealing the marnoso arenacea reservoir structural analyses focused on selected thrust folds exhibiting clear relations between surface seepage and brittle elements associated with the fold various scenarios potentially explaining mud volcanism and venting over the crestal region of the thrust related folds are discussed with respect to fluid pressure state and the development of second order fault and fracture sets that are observed to control surface fluid expulsion it is proposed that mud volcanism can be potentially triggered by first order fault failure cycles during which the overpressured fluid is released during faulting events past anomalous eruptions associated with strong earthquakes seem to support this hypothesis the relatively quiescent but continuous activity of the current pede apennine mud volcanoes could instead reflect a short lived leakage of overpressured fluids along permeable fractures faults expansion of methane contained in the rising mud may assist this process fundamentally

changes in braided river morphology resulting from aggradation and degradation forty three experiments were completed in a large flume 1 8 x 18 3 m to examine the effects of sediment load sediment size and channel gradient on braided river morphology the laboratory results were supported by field research and analogs from the published literature subaerially exposed braid bars were formed by the dissection and further accretion of stalled linguoid dunes which are actively migrating bedforms bar forming processes and channel dynamics were the same in both sand and gravel bed channels however linguoid dunes stalled and were transformed into braid bars more frequently in gravel bed channels and therefore gravel bed channels were more intensely braided aggradation resulted in the development of more bars rather than in an increase in the size of preexisting braid bars the number of actively migrating linguoid dunes also increased with sediment load in the highly mobile sand bed channels conversely in degrading channels the number of braid bars decreased and average bar

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

formation of braided river floodplains waimakariri river new zealand floodplains along the braided gravel bed waimakariri river are discontinuous although generally extensive landforms composed predominantly of gravel bars capped with vertically accreted fines in order of importance three mechanisms lead to floodplain formation river bed abandonment by lateral migration of the braid train initiates the formation of the largest floodpiains which usually occur downstream of tributary fans and valley bedrock spurs in the headwater reaches localized river bed aggradation during high magnitude events leads to floodplain formation by producing a surface resistant to erosion by lesser events due to either the coarse nature of the deposit or by its elevation over the river bed or both the least important mechanism initiating floodplain development is localized river or channel incision a six stage model is proposed for the sequential development of floodplains on the waimakariri river from i active river bed ii stabilizing bar iii incipient floodplain iv established floodplain v mature floodplain and to vi terrace two mechanisms lateral migration by the braid train and reactivation of abandoned channels within floodplains operating separately or in combination are responsible for floodplain reworking and their relatively young age 250 years clearly braided rivers can construct substantial areas of well developed floodplain

cellular modelling as a tool for interpreting historic braided river evolution abstract results are presented from a new cellular model of braided river dynamics that simulates flow sediment transport morphological change and the effects of braidplain vegetation this model is used to investigate the effect of changes in upstream sediment supply on braided river systems over simulation periods of 200 years modelled changes in channel morphology associated with both aggradation and degradation were seen to be consistent with those reported in the literature in addition simulation results allowed the identification of diagnostic characteristics of aggrading and degrading reaches in the form of relationships between the age extent and relative elevation of fluvial surfaces interpretation of spatial patterns of valley floor surface characteristics in the avoca river new zealand on the basis of these relationships allowed the identification of channel reaches that appear to be experiencing either aggradation or degradation these inferences are shown to be consistent with independent evidence of spatial patterns of sediment supply to the main valley floor derived from aerial photographs and an existing sediment source inventory these results illustrate the potential for using cellular models to develop an improved understanding of natural river behaviour

mud volcanism an updated review abstract mud volcanism or sedimentary volcanism represents one of the most intriguing phenomena of the earth s crust with important implications in energy resource exploration seismicity geo hazard and atmospheric budget of greenhouse gases since the first review papers were issued at the beginning of 2000s a large amount of new geological geophysical and geochemical data has been acquired which clarified ambiguous concepts and significantly improved our knowledge of mud volcanism here we offer an updated review of the knowledge and implications of mud volcanoes with emphasis on the terminology used to describe different processes and structures the physical chemical and morphological characteristics of the several fluid emission structures the chemical properties of the released fluids in particular the molecular and isotopic composition of the gas the mud volcano formation dynamics and the several implications for petroleum exploration geo hazards and global atmospheric methane budget this review integrates new fluids data collected in azerbaijan and is complemented with field observations from various mud volcano provinces worldwide although the total number of mud volcanoes on earth is still uncertain 600 main onshore structures with a large variety in shapes and sizes are documented in recent global data sets and several thousand are assumed to exist in the oceans it is clear that a mud volcanoes are broadly distributed throughout the globe in active margins compressional zones of accretionary complexes thrust and overthrust belts passive margins deep sedimentary basins related to active plate boundaries as well as delta regions b they are specifically located in hydrocarbon bearing basins along anticline axes strike slips and normal faults and fault related folds in petroleum systems c they represent a specific category of natural gas oil seepage manifestation often related to deep and pressurised reservoirs d the main engine driving mud volcanism is given by a combination of gravitative instability of shales and fluid overpressure build up followed by hydrofracturing e hydrocarbons are generally of thermogenic origin while microbial gas is released in only a few cases mud volcanism on other planets e g mars and titan and microbial activity associated with gas seepage represent emerging issues and opportunities for future research

sediment transfer and transformation of an alluvial valley floor the river south tyne northumbria u k the amounts of alluvial storage and the mechanisms responsible for the dispersal of sediment associated with historic metal mining are examined for a 115 year timespan on a 22 km reach of the river south tyne northern england analysis of lateral and vertical channel change over this period the extent of actively reworked gravels and identification of metals in alluvial units show five sedimentation zones separated by more stable reaches aggradation in the late nineteenth century was followed by a period of storage and local reworking and then incision some reaches show short term storage of sediment injected from tributaries which may be dispersed by floods there is some evidence of transfer of sediment bodies downvalley within sedimentation zones and of a sediment wave movement between zones in lower parts of the south tyne investigated present day incision the variation in the area of actively reworked gravel spreads and the widespread dispersal of fine grained toxic metal mining wastes all have practical implications the intricate response of the channel system to historic changes in sediment supply is not readily described by either a complex response model or a simple translatory wave

three dimensional fem derived elastic green s functions for the coseismic deformation of the 2005 mw 8 7 nias simeulue sumatra earthquake using finite element models fems we examine the sensitivity of surface displacements to the location of fault slip topography and three dimensional variations in elastic moduli in the context of a 2 d infinite thrust fault we then evaluate the impact of these factors and fault geometry on surface displacements and estimates of the distribution of coseismic slip associated with the 2005 m w 8 7 nias simeulue sumatra earthquake topographic effects can be significant near the trench where bathymetric gradients are highest and the fault is closest to the free surface variations in young s modulus can significantly alter predicted deformation surface displacements are relatively insensitive to perturbations in poisson s ratio for shear sources but may play a stronger role when the source has a dilatational component if we generate synthetic displacements using a heterogeneous elastic model and then use an elastic half space or layered earth model to estimate the slip distribution and fault geometry we find systematic residuals of surface displacements and different slip patterns compared to the input fault slip model the coseismic slip distributions of the 2005 earthquake derived from the same fault geometry and different material models show that the rupture areas are narrower in all tested heterogeneous elastic models compared to that obtained using half space models this difference can be understood by the tendency to infer additional sources in elastic half space models to account for effects that are intrinsically due to the presence of rheological gradients although the fit to surface observations in our preferred 3 d fem model is similar to that from a simple half space model the resulting slip distribution may be a more accurate reflection the true fault slip behavior

fluvial fan deltas linking channel processes with large scale morphodynamics 1 alluvial fan deltas are built by aggrading and avulsing river channels a numerical model of flow and sediment transport in channels is combined with a condition for channel avulsion to describe evolution of the fan surface the model combines elements of two recent approaches 1 diffusional models of depositional basin filling which describe the evolution of overall morphology and 2 cellular models of channel evolution which provide simplified descriptions of channel dynamics here the cellular formulation is used simply as a template for discretizing a standard set of equations describing flow and sediment transport within channels the basic formulation is thus grid invariant and the results are in actual rather than arbitrary time and length scales the model captures the interaction between microscale channel morphodynamics including converging and diverging flow and avulsion and morphodynamics at the macroscale fan it provides a starting point for the study of a wide range of topics including the three dimensional stratigraphy of fan delta deposits and the response of fan deltas to engineering activities

incision and morphologic evolution of an alluvial channel recovering from hydraulic mining sediment hydraulic gold mining in the sierra nevada california produced such a large volume of sediment from 1853 to 1884 that channels could not carry a substantial proportion of the delivered sediment the lower bear river aggraded as much as 5 m and underwent a major avulsion during the 1870s channel morphology continues to respond to these changes more than 100 years after the cessation of most hydraulic mining textures of mine tailings and older alluvium are contrasted and channel incision and channel shape changes from 1930 to 1985 are documented unlike the yuba and sacramento rivers the lower bear river had not returned to pre mining base levels by 1950 as sediment loads decreased nor were incision rates or morphological change governed by reduced sediment loads below dams built in 1928 and in the mid 1960s channel stability was due to resistance of a cohesive stratum on the channel bed an episode of channel down cutting was instigated by a moderately large flood in december 1955 that pierced the cohesive layer and was sustained through the 1970s by moderate magnitude floods the 1955 flood did not directly erode large volumes of sediment but it destabilized the channel allowing smaller floods to erode the channel at an accelerated rate episodic channel bed incision is contrasted to progressive morphologic changes cross section shape narrowed and deepened steadily from 1930 through the mid 1970s as the channel was superimposed onto cohesive older alluvium progressive deepening set up a positive feedback that ensured the ultimate penetration of the paved bed channel morphologic readjustment from the avulsion thus was both progressive and episodic

a new model of the petroleum system in the northern apennines italy a geochemical study on fluids from selected spontaneous seepages and drilled wells was carried out together with geologic investigation and deep cross sections reconstruction to examine the petroleum system in the western northern apennines foothills the hydrocarbons occurring in the miocene foredeep units that form the reservoirs are commonly interpreted as generated in a source reservoir system however the low total organic carbon its elevated dilution in the sediment pile and the limited amount of successions that entered in the oil window indicate a low potential for the hydrocarbons generation the structures deformation in the northern apennines foothills is mainly late miocene to pliocene in age and involves successions that are progressively younger towards southeast the earlier structure forms the salsomaggiore anticline in the western sector the comparison of the fluids from the wells and the mud volcanoes shows high geochemical and thermal history similarities saline waters originate from the connate pore water entrapped in the miocene reservoir rocks during their deposition the gaseous hydrocarbons are a mixture of secondary biogenic methane and primary and secondary thermogenic gases the associated oils show both early and late maturities these evidences account for different generation and migration steps depending on burial conditions and deformation time the various reservoirs appear confined by the thrust detachment at different depths and by the occurrence of reactivated lateral ramps these results suggest the occurrence of a common source rock deeper than the tertiary reservoir units which progressively entered in the oil window this source rock could have wide lateral extension at least comparable with the width of the studied area and represent a prime exploration target to evaluate the undiscovered oil and gas resources

simulation of braided river flow using a new cellular routing scheme abstract results are presented from a numerical simulation of two dimensional flow patterns in a braided river using a simple cellular routing scheme the results of the routing scheme are compared with field measurements of discharge per unit width obtained within the study reach at low flow and for higher flows with the predictions of a more sophisticated hydraulic model that solves the two dimensional shallow water form of the navier stokes equations an assessment is made of the sensitivity of the routing scheme to variations in the values of its main parameters and appropriate values are determined based on the physical characteristics of the study site and available flow measurements it is shown that despite the simple approach adopted by the cellular routing scheme to simulate processes of water redistribution it is able to replicate accurately both the field data and the results of the more sophisticated hydraulic model these results indicate that the routing scheme outlined here is able to overcome some of the limitations of previous simple cellular automata models and may be suitable for use in modelling bedload transport and channel change in complex fluvial environments as such this research represents a small and ongoing contribution to the field of numerical simulation of braided river processes

molecular stratigraphy a new tool for climatic assessment variations in sea surface temperatures over the past 500 000 years are inferred from the relative abundance behaviour of two organic compounds c37 alkenones over the upper 8 metres of a sediment core from the eastern equatorial atlantic this molecular record ascribed to contributions from prymnesiophyte algae correlates well with the variations in the 18 signal for the calcareous skeletons of certain planktonic foraminifera thus providing the first demonstration of a new stratigraphical technique which may be especially valuable where methods based on carbonate 18 fail

dinosterane and other steroidal hydrocarbons of dinoflagellate origin in sediments and petroleum abstract the steroidal alkanes of a selection of sediments and oils have been examined by gc ms with multiple metastable reaction monitoring specific 4 methyl sterane isomers have been identified by comparison with isomers synthesized from sterols isolated from dinoflagellates an immature marine oil shale and two mature marine oils of triassic to early cretaceous age contained high concentrations of c30 steranes comprising desmethyl 24 ethyl 4 methylcholestane and 4 23 24 trimethylcholestane dinosterane isomers an immature non marine oil shale and two non marine oils of cretaceous to eocene age contained stereoisomers of 24 ethyl 4 methylcholestane as the dominant c30 steranes reaction monitoring analyses in gc ms are particularly suited to unravelling complex distributions of homologous and stereoisomeric steroids encountered in oils and their source rocks

extreme efficiency of mud volcanism in dewatering accretionary prisms drilling results from two mud volcanoes on the mediterranean ridge accretionary complex as well as bottom sampling and the wealth of geophysical data acquired recently have provided fundamental knowledge of the 3d geometry of mud extrusions mud volcanism is generally related to buoyancy density inversion and is triggered by the collision of the african and eurasian blocks forcing undercompacted clayey sediments to extrude along faults in the central and hinterlandward parts of the prism volumetric estimates of extruded mud in several well studied areas were based on pre stack depth migrated seismic profiles across the entire up to 150 km wide prism the resulting volumes of mud were combined with ages from mud dome drilling so that rates of mud extrusion were obtained subtracting the solid rock mass from the bulk mud volume using physical property data fluid flux as a function of mud volcanism alone has been quantified for the first time the volume of fluid extruding with the mud is found to be variable but reaches up to 15 km3 fluid per km trench length and ma along cross sections with abundant mud volcanoes such large fluid quantities in a region some 50 150 km behind the deformation front exceed estimates from those elsewhere where undoubtedly the majority of the interstitial fluid is lost due to compaction such fluids near the backstop are likely to result predominantly from mineral dehydration and diagenetic reactions at depth and consequently provide a window to understand deeper processes along the deep decollement more importantly the enormous rates with which such fluids and liquified mud escape along the out of sequence faults alter fluid budget calculations in subduction zones drastically

elliptical mud volcano caldera as stress indicator in an active compressional setting nirano pede apennine margin northern italy the relations between mud volcanism and active tectonic strain were investigated at the nirano mud volcano field nmvf near the active pede apennine thrust front of the northern apennines thrust and fold belt italy active fluid release occurs through numerous vents within an elliptical depression developed over the crest of a thrust related anticline this depression is interpreted as a caldera collapse like structure that may have developed in response to the deflation of a shallow mud chamber triggered by eruption and sediment fluid evacuation events like many volcanic calderas the nmvf caldera is elongated nearly parallel to the direction of least horizontal compressive stress s h and is thus deduced to reflect the regional tectonic stress axes it is concluded that mud volcano calderas exhibit mechanical similarities to the igneous analogs and that the methods used in this first test could be applied to other calderas imaged by seismic data and in the field

geochemical characterization of the nirano mud volcano italy abstract the nirano mud volcano is located in the western sector of the modena apennine margin italy it represents one of the most spectacular phenomena of sedimentary volcanism in the entire italian territory and is among the largest in europe here numerous aligned gryphon clusters and seeping pools constantly burst gas and mud inside a morphological depression besides the obvious surface expressions of these emission spots until now the type and amount of gas released in the rest of the large nirano caldera zone remained unknown an extensive geochemical soil gas survey o2 n2 co2 ch4 222rn he h2 and light hydrocarbons and exhalation fluxes co2 and ch4 was carried out inside the mud volcano field with the aim of identifying soil degassing distribution and to estimate the micro and macro seepage budget for both co2 and ch4 soil gas data highlight the presence of two zones characterized by high concentrations and flux values these enhanced seepage zones are located in the sw and ne sectors of the mud volcano suggesting that the enhanced gas emissions present in the peripheral zones are controlled by caldera collapse structures the most significant co2 flux up to 91 g m 2 d 1 and 222rn anomalies are located in the central part of the crater in correspondence of a morphological escarpment here we infer the presence of a buried tectonic system of collapsed terraces that facilitate fluids degassing in contrast ch4 fluxes show a scattered distribution and low values mean 221 mg m 2 d 1 overall the ch4 degassing budget is low 27 09 t km 2 y 1 when compared with other italian mud volcanoes this could be related to a relative low emission activity during the period of the geochemical survey and to a more homogeneous dilution of surface distribution of the emission point s chemical and isotopical composition of the gas discharged from the active gryphons is methane dominated and the thermogenic signature ranging from 41 to 47 suggests a deep reservoir source this conclusion is supported by noble gas measurements he ne ar kr xe conducted in the pore water phase of the emitted mud indicating a secondary gas exchange occurring at a depth of a few kilometers the geochemical anomalies found in this study successfully predicted the occurrence of new degassing phenomena towards the ne sector of the caldera indeed recently i e after the survey data acquisition new manifestations of mud and gas emissions appeared in the north eastern edge of the caldera