geochemistry of interstitial gases in quaternary sediments of the gulf of california abstract interstitial gases from the deep sea drilling project dsdp ipod leg 64 sites 474 477 479 and 481 in the gulf of california have been analyzed by gas chromatography and stable isotope mass spectrometry in order to evaluate their compositions in terms of biogenic and thermogenic sources the hydrocarbon gas c 1 c 5 concentrations were comparable to the shipboard data and no olefins could be detected the 13 c data for the ch 4 confirmed the effects of the thermal stress on the sedimentary organic matter in that the values were typically biogenic near the surface and become more depleted in 12 c vs depth at sites 474 478 and 481 the ch 4 at site 477 was the heaviest in 13 c and at site 479 it did not show a predominant high termperature component the co 2 at depth from most sites was of a primarily thermogenic origin from carbonate decomposition

controls on the geomorphic expression and evolution of gryphons pools and caldera features at hydrothermal seeps in the salton sea geothermal field southern california abstract in the salton sea geothermal field in southern california expulsion of gas sediment and water creates unique geomorphic features similar to those seen on the surface of dormant mud volcanoes these include pools of water or highly fluid mud named mud pots and 0 5 to 2 5 m tall gryphons the features vary in size shape and type of eruptive activity and change form over time to evaluate controls on the surface morphology and evolution of these features we used repeated differential gps surveys observations of eruptive activity and measurements of erupted mud properties to document the physical characteristics and changes in the system over a 28 month period we find that the morphology of the gryphons is primarily a function of the mud expulsion style taller 1 5 m to 2 4 m gryphons form where narrower vents 5 cm to 15 cm diameter expel mud to the surface in discrete strombolian type eruptions caused by individual gas bubbles pushing mud up through the gryphon conduit and exploding at the surface smaller 0 6 m to 1 5 m gryphons form where wider vents allow a greater amount of gas to pass through which creates 0 25 to 1 m diameter mud craters that bubble continuously often from multiple points within the crater although viscous mud is required to create these positive topographic features variations in erupted mud temperature 30 c to 68 5 c density 1 44 g cm 3 to 1 59 g cm 3 and water content 36 to 44 between different gryphons did not correlate with gryphon size all the active gryphons experienced periods of growth and erosion over the study period due to changes in the degree of activity or small variations in the vent locations within the gryphons but the net change in height distributions over time was negligible pools directly adjacent to gryphon clusters are surficial features whose water level depends on seasonal rainfall and temperature isolated pools are also present and do not show similar response to seasonal changes suggesting that these pools are connected to the local groundwater system although changes in vent morphology and activity do occur the new data demonstrate that the system is steady state in terms of the height distribution of the gryphons and the location of the main seeps most of the gryphons occur in clusters that are surrounded by caldera like depressions that range from 10 to 25 m in diameter mud expelled from the gryphons is largely contained within the caldera depressions and we infer that subsidence of the calderas accounts for the lack of large scale build up of material in the surrounding area this study provides the first examination of the processes controlling the morphology of these features and the results may help to understand the dynamics and temporal evolution of gryphons which are found in both hydrothermal systems and on dormant mud volcanoes

a brine interface in the salton sea geothermal system california fluid geochemical and isotopic characteristics data from 71 geothermal production intervals in 48 wells from the salton sea geothermal system ssgs indicate that fluids in that system cluster into two distinct populations in terms of their salinity and their stable isotopic compositions the distinctive hot hypersaline brine typically 20 wt total dissolved solids for which the ssgs is known is overlain by a cooler 260 c fluid with distinctly lower salinity typically 10 wt total dissolved solids hypersaline brines have high and rather consistent 18o shifts produced by water rock interaction and have a very narrow range in d values low tds fluids on the other hand show a wide range in both d and 18o production of both types of fluid from closely spaced geothermal wells in many regions of the ssgs indicates that a relatively sharp salinity interface exists over much of the field the fluid interface typically cross cuts sedimentary bedding but is consistently found where reservoir temperatures are approximately 260 c at these temperatures hypersaline brines have densities of approximately 1 0 gm cm3 while the low tds fluids have densities as low as 0 85 gm cm3 this stable density stratified interface acts as a barrier to convective heat and mass transfer in the ssgs isolating the hypersaline reservoir from overlying dilute fluids a lithologic cap implied by previous ssgs models is unnecessary in such a stratified system since heat and mass transfer across the interface must occur by slow conductive diffusional and interface mixing processes regardless of local permeability

sediment hosted geothermal systems review and first global mapping abstract sediment hosted geothermal systems shgss are hybrid geological systems where volcanic and sedimentary domains interact leading to mixtures of inorganic and organic gases typically characterized by geothermal thermometamorphic or mantle derived co2 and biotic microbial or thermogenic ch4 shgss occur in sedimentary basins crossed by magmatic intrusions or involved in volcanic plumbing systems these systems can be of considerable interest for petroleum exploration and natural greenhouse gas emission studies but systematic studies for their characterization and worldwide distribution are missing here we provide a review of shgss identified so far and propose methodological criteria for their definition and identification based on integrated geological and gas geochemical parameters we find that shgss are typically characterized by a fluids dominated by mantle or decarbonation methamorphic co2 50 vol b considerable amounts of ch4 and heavier hydrocarbons at least 1 5 vol generally up to 30 40 vol produced by microbial or thermogenic degradation of organic matter hosted in sedimentary rocks c tectonically active sedimentary basins back arc rift zones and foredeep generally hosting petroleum fields and within 300 km from recent or ancient volcanic centers this analysis resulted in a global map including a first set of 33 shgss located in north america central and eastern europe far east eastern oceania and northern new zealand and a second set of potential shgs prone areas occurring also in south america north africa middle east and kamchatka the present shgs map can evolve on the basis of more detailed geological analysis and new gas geochemical data

hydrothermal petroleum genesis migration and deposition in guaymas basin gulf of california hydrothermal activity and seabed mounds have been explored in guaymas basin by the deep sea drilling project dsdp piston coring dredging and diving with the deep submersible research vessel dsrv alvin sedimentary organic matter derived primarily from immature degraded microbial detritus is easily converted to petroleum under the hydrothermal regime these petroleums are mature and migrate in the fluids and by diffusion to the seabed the fluid migration is aided by near critical aqueous solution and supercritical carbon dioxide and hydrocarbons petroleum compositions vary from condensates to naphthenic to waxy all with significant amounts of asphaltenes and hydrothermal products such as olefins and toxic polynuclear aromatic hydrocarbons pah the heavy ends condense at the seabed depositing mainly as a cement with the sulfides and other minerals and to a lesser extent as entrapped oil and crystalline wax in vugs and conduits of the mounds the pah are high temperature resynthesis aromatiza

petroleum generation an easy and widespread process in hydrothermal systems an overview abstract the conversion of organic matter to petroleum products by hydrothermal activity is an easy process occurring in nature in many types of environments geologically immature organic matter of marine sediments has been shown to be altered to petroleum products by this process in the guaymas basin escanaba trough bransfield strait and atlantis ii deep and this process probably occurs elsewhere in active sedimented rift systems contemporary organic detritus and or viable microorganisms are also converted in part to petroleum like products when they become entrained by turbulent mixing into hydrothermal vent waters resulting in their instantaneous hydrous pyrolysis this latter case occurs in hydrothermal vent fields without a sedimentary cover emanating directly from oceanic ridges as for example on the east pacific rise at 13 n and 21 n and on the mid atlantic ridge at 26 n this process is probably also ubiquitous for all actively venting sediment starved oceanic ridges the hydrocarbon products generated in these areas have been compared in terms of composition organic matter sources and analogy to reservoir petroleum they represent a major carbon source for chemosynthetic assimilation by vent biota and are compositionally similar to normal petroleum

comprehensive atlas of stress trajectory patterns and stress magnitudes around cylindrical holes in rock bodies for geoscientific and geotechnical applications abstract this study presents a comprehensive atlas comprising maps and graphs which quantify the wide range of possible stress states around circular cylindrical cavities when subjected to the full range of far field stress conditions and internal net pressures a greater understanding of the principal stress trajectories and related stress magnitudes around stressed cylindrical holes in rock formations significantly aids the design of safer and more stable wellbores advances our capacities in hydraulic fracturing and provides additional insights into the nature and stability of volcanic dikes salt domes and caverns used for hydrocarbon and other fluid storage the algorithms used in our study systematically non dimensionalize the analytical kirsch equations using two critical parameters to scale the variable boundary conditions 1 the bi axial stress scalar describes the far field stresses at all depths and for each of the formations penetrated by a cylindrical borehole or natural liquid filled pipe by describing the anisotropy of the two far field principal stresses and 2 the frac number f specifies the net pressure on the cylindrical hole as it relates to the natural background stress in the host rock and the pressure in the penetrated formation at each depth manipulation of these two governing parameters f enables us to view and monitor the stress trajectories in the host rock around a cylindrical hole at any given depth additionally the neutral point locations and their effects on the principal stress orientations near the cylindrical hole have been more thoroughly investigated than in earlier studies the neutral points form the boundaries for the stress cage in overbalanced cylindrical cavities and for the complimentary fracture cage in underbalanced cavities the understanding of stresses induced around cylindrical holes in a rock formation is paramount in geotechnical analyses and stability appraisals of manmade cylindrical holes as well as for the geoscientific interpretation of piercing by cylindrical fluid filled pipes our stress atlas aims to provide fundamental insight and practical support for such analyses

fluid density distribution in a high temperature stratified thermohaline system implications for saline hydrothermal circulation density distribution within the salton sea geothermal system of fluids ranging from 20 c to 325 c has been computed using chemical and thermal data from geothermal production well tests and curve fit models of nacak chloride solution properties density corrections can easily be made to 0 01 g cm3 for solute effects of each of the dominant chloride salts as well as pressure above vapor saturation field data on dissolved co2 is too sparse to routinely compute a correction however this moderately but variably abundant component can be shown to produce only minor 0 01 g cm3 errors in density estimates fluid density within the shallow cool 20 wt the density of brine climbs rapidly to near 1 0 g cm3 as the salinity increase across this interface overwhelms the thermal effect on fluid density this steep density gradient precludes all but diffusional conductive or perhaps double diffusive convective mass and heat transfer in this transitional regime measurement uncertainties for reservoir depths temperatures and salinities commonly exceed errors of our density model limiting the accuracy of details in our modeled density distribution gross scale relationships of this salinity stratified geothermal system are however apparent permitting rational discussion of extrapolations to conditions beneath the presently explored reservoir and inference of dynamics during the systems evolution

abrupt increase in greenland snow accumulation at the end of the younger dryas event the warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate the best known of which is the younger dryas event1 despite much study of the causes of this event and the mechanisms by which it ended many questions remain unresolved1 oxygen isotope data from greenland ice cores2 4 suggest that the younger dryas ended abruptly over a period of about 50 years dust concentrations2 4 in these cores show an even more rapid transition 20 years this extremely short timescale places severe constraints on the mechanisms underlying the transition but dust concentrations can reflect subtle changes in atmospheric circulation which need not be associated with a large change in climate here we present results from a new greenland ice core gisp2 showing that snow accumulation doubled rapidly from the younger dryas event to the subsequent preboreal interval possibly in one to three years we also find that the accumulation rate change from the oldest dryas to the bo11ing allerod warm period was large and abrupt the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the north atlantic climate system

evidence of the younger dryas in central america abstract three sites provide records that address whether the younger dryas was manifest in central america marine records from barbados and the cariaco basin are discussed as well as possible climatic forcing mechanisms sequences from montane la chonta bog costa rica and lowland lake quexil guatemala record a temperature decline of 1 5 2 5 c dated between 11 070 10 400 14c years bp and ca 12 000 10 300 14c years bp respectively the record from lake la yeguada panama does not include cooling although significant reorganization of local communities occurred during the younger dryas chronozone colder tropical ssts throughout deglaciation contributed to sub regional climatic variation more intense monsoonal activity and cooler air temperatures however the temperature reversals are not associated with the coldest tropical ssts which occurred during meltwater pulses the temperature reversals appear to be a response to extra tropical conditions presumably in the north atlantic which suggests that younger dryas cooling extended as far south as costa rica in panama monsoonal conditions may have blocked cooler temperatures precipitation continued to increase throughout deglaciation due to strong forcing by seasonal solar insolation in central america while desiccation events occurred to the north and south

when mud volcanoes sleep insight from seep geochemistry at the dashgil mud volcano azerbaijan the worlds 1500 mud volcanoes are normally in a dormant stage due to the short duration of eruptions their dormant stage activity is often characterized by vigorous seepage of water gas and petroleum however the source of the fluids and the fluid rock interactions within the mud volcano conduit remain poorly understood in order to investigate this type of activity we have combined satellite images with fieldwork and extensive sampling of water and gas at seeping gryphons pools and salsa lakes at the dashgil mud volcano in azerbaijan we find that caldera collapse faults and e w oriented faults determine the location of the seeps the seeping gas is dominated by methane 94 9 99 6 with a 13c v pdb in the 43 9 to 40 4 range consistent throughout the 12 analysed seeps ethane and carbon dioxide occur in minor amounts seventeen samples of seeping water show a wide range in solute content and isotopic composition pools and salsa lakes have the highest salinities up to 101 043 ppm cl and the lowest 18o v smow values 1 4 the mud rich gryphons have low salinities 18 000 ppm cl and are enriched in 18o 18o 4 6 the gas geochemistry suggests that the gases migrate to the surface from continuously leaking deep seated reservoirs underneath the mud volcano with minimal oxidation during migration however variations in gas wetness can be ascribed to molecular fractionation during the gas rise in contrast the water shows seasonal variations in isotopic composition and surface evaporation is proposed as a mechanism to explain high water salinities in salsa lakes by contrast gryphons have geochemical signals suggesting a deep seated water source these results demonstrate that the plumbing system of dormant mud volcanoes is continuously recharged from deeper sedimentary reservoirs and that a branched system of conduits exists in the shallow subsurface while the gas composition is consistently similar throughout the crater the large assortment of water present reflects the type of seep i e gryphons versus pools and salsa lakes and their location within the volcano our data highlight the importance of a carefully planned sampling strategy when the target is water geochemistry whereas the methane content and isotopic composition is relatively independent of the particular seep morphology

the el abra stadlal in the eastern cordillera of colombia south america abstract the el abra stadial is a climatic cooling event defined in the eastern cordillera of colombia which corresponds both in timing and intensity to the younger dryas climatic oscillation of the northern north atlantic region the stadial was preceded by the relatively warm guantiva interstadial and followed by the warm holocene colder climatic conditions during the el abra stadial caused a 400 m lowering of the upper andean forest limit below its altitudinal location during the preceding guantiva interstadial translated in temperature change this represents a drop in mean annual temperature of approximately 2 to 3 c the lowering of the upper forest limit and inferred temperature change for the el abra stadial compared to late holocene conditions are in the order of 600 m and 4 c respectively the transition of the guantiva interstadial to the el abra stadial has been radiocarbon dated at 11 210 90 bp and 10 820 60 bp climatic warming may have started shortly after 10 380 90 bp and near present day temperatures were reached at least as early as 8920 100 bp maximum cooling was probably attained between 10 800 bp and 10 300 bp further ams radiocarbon dating is planned to establish more exactly the timing of the el abra stadial a glacial advance of el abra age the bocatoma stade has been recognized in the highest part of the colombian eastern cordillera the sierra nevada del cocuy during this advance glaciers extended some 700 m lower than at present a climatic cooling event of el abra age associated with shifts of the upper andean forest limit and glacial advances has also been recognized in other parts of andean colombia including the central cordillera and the sierra nevada de santa marta

development and growth of recently exposed fumarole fields near mullet island imperial county california abstract new field observations aerial surveys lidar measurements and laboratory studies of mud samples 2006 to 2012 are reported of several formerly submerged fumarole complexes that are presently undergoing surface exposure as the salton sea level drops some remain submerged as of this writing 2012 the fumarole fields range in area from 1000 to 50 000 m2 they consist of hundreds of warm to boiling hot gryphons mud volcanoes salses mud pots and countless active gas vents unusually shaped mud volcanoes in the form of vertical tubes with central vents were observed in many places since exposure began in 2007 the surface morphology has changed dramatically with a trend toward more and growing gryphons larger mud pots and the development of sulfur vents chemical analysis of mud from several gryphons revealed the presence of the ammoniated sulfate minerals boussingaultite and lecontite among other more common sulfates with other geothermal features the fumaroles define a well defined lineament marking the trace of a probable fault a model for the development of gryphon morphology is presented

remotely sensed ammonia emission from fumarolic vents associated with a hydrothermally active fault in the salton sea geothermal field california 1 airborne hyperspectral imaging surveys were conducted over a geothermally active region straddling the southeastern shore of the salton sea in southern california the imagery was acquired across the 7 6 13 5 m longwave infrared region with a ground sample distance of approximately 1 m prominent thermal hot spots associated with fumaroles along a known fault line were observed to coincide with emission of free ammonia presumed to originate from geothermally induced pyrolytic decomposition of nitrogenous compounds that permeate the lake water sediment and adjacent agricultural terrain it is shown that the inferred fluxes of ammonia constitute a significant fraction 10 25 of the total atmospheric ammonia burden assessed for the salton sea environs and represent a previously unreported source for that locale

phenols in hydrothermal petroleums and sediment bitumen from guaymas basin gulf of california the aliphatic aromatic and polar nso fractions of seabed petroleums and sediment bitumen extracts from the guaymas basin hydrothermal system have been analyzed by gas chromatography and gas chromatography mass spectrometry free and silylated the oils were collected from the interiors and exteriors of high temperature hydrothermal vents and represent hydrothermal pyrolyzates that have migrated to the seafloor by hydrothermal fluid circulation the downcore sediments are representative of both thermally unaltered and thermally altered sediments the survey has revealed the presence of oxygenated compounds in samples with a high degree of thermal maturity phenols are one class of oxygenated compounds found in these samples a group of methyl dimethyl and trimethyl isoprenoidyl phenols c27 c29 is present in all of the seabed nso fractions with the methyl and dimethyl isoprenoidyl phenols occurring as major components and a trimethyl isoprenoidyl phenol as a minor component a homologous series of n alkylphenols c13 c33 has also been found in the seabed petroleums these phenols are most likely derived from the hydrothermal alteration of sedimentary organic matter the n alkylphenols are probably synthesized under hydrothermal conditions but the isoprenoidyl phenols are probably hydrothermal alteration products of natural product precursors the suites of phenols do not appear to be useful tracers of high temperature hydrothermal processes

cold climatic episode of younger dryas age in tierra del fuego pronounced climatic change during the last glacial maximum is recognized as global in extent and has been attributed to orbital forcing1 not readily explained in a global context because of the equivocal nature of the evidence are the late glacial climatic events of short 100 1 000 yr duration the cold climate of the younger dryas chron 11 000 10 000 yr bp for example is known to have been particularly pronounced over the north atlantic and parts of europe and north america2 3 whereas in the southern hemisphere cold conditions for that time are not well established here we present evidence for late glacial climatic cooling in southernmost south america from studies of radiocarbon dated glacial and pollen stratigraphy at sites along the beagle channel in tierra del fuego where a forest tundra tension zone in the region is especially sensitive to shifting climate we conclude that the cold episode corresponds with the time of the younger dryas in europe when a drop in temperature ascribed most recently to colder sea surface temperatures and production rate of deep water in the north atlantic4 5 apparently occurred worldwide

sulfate mineralogy of fumaroles in the salton sea geothermal field imperial county california abstract the salton trough lies in the transition between the san andreas fault and oblique spreading centers and transform faults in the gulf of california the salton sea geothermal field is the northernmost expression of those spreading centers in 2007 two ammonia emitting fumarole fields that had been submerged beneath the salton sea were exposed for the first time in nearly 50 years as the sea level continued to drop these fields have developed a number of boiling pools mud pots gryphons and a unique suite of ammonium sulfate minerals these have been studied over time with long wave infrared remote sensing coupled with ground truth surveys backed by laboratory analyses of the minerals many vents lie at the center of concentric rings of mineralization with systematic occurrence of different minerals from center to edge three semi concentric zones fumarole transition and evaporite have been defined with respect to ammonia emitting vents and bubbling pools the scale of these zones range from several meters localized around individual vents to that of the fumarole fields as a whole the fumarole zone is closest to the vents and locally contains cavernous sulfur crystals and significant deposits of gypsum mascagnite boussingaultite and other ammonium sulfates the transition zone comprises a dark brown surficial band of inconspicuous sodium nitrate underlain by anhydrite bassanite that is thought to have formed by ammonia oxidizing microbes interacting with the ammonium sulfates of the outer fumarole zone the evaporite zone is the outermost and contains blodite thenardite and glauberite which are typical of the sulfates associated with the shoreline of the salton sea remote sensing has shown that the mineral zones have remained relatively stable from 2013 to 2017 with minor variations depending on rainfall temperature and levels of agricultural runoff

analysis of petroleum fractions by tlc fid applications to petroleum reservoir description abstract thin layer chromatography and flame ionization detection iatroscan tlc fid offers a rapid and accurate method for quantifying saturated and aromatic hydrocarbons and resin asphaltene fractions in solvent extracts of petroleum source rocks reservoir rocks and crude oils while the instrument is superficially simple special precautions need to be taken in calibration and parameter setting due to complexities arising from the operational characteristics of the detector system nevertheless the technique offers superior speed and precision to conventional mplc analysis of petroleum fractions this paper describes the choice of operational parameters provides comparison with the traditional group type analysis technique mplc and presents some geochemical applications

rankine models for time dependent gravity spreading of terrestrial source flows over subplanar slopes geological mass flows extruding from a point source include mud lava and salt issued from subsurface reservoirs and ice from surface feeders the delivery of the material may occur via a salt stock a volcanic pipe for magma and mud flows or a valley glacier for ice all these source flows are commonly skewed by a superposed far field velocity vector imposed by the topographic slope and thus develop plumes having a wide range of shapes the morphological evolution of the perimeter of the plumes in plan view can be simulated by varying the key parameters in a simple analytical flow description on the basis of rankine equations our model systematically varies the strength of the point source relative to the downslope far field velocity of its expelled mass the flow lines are critically controlled by the relative speed of the two rates which can be concisely expressed by the dimensionless rankine number rk introduced in this study for steady flows plume widths can be expressed as a function of rk the viscosity of the rock mud or lava mass involved in the gravity flow affects rk and thus the appearance of the plumes for unsteady source strength rk becomes time dependent and the plume width varies over time the model flow shapes suggest that the plume shapes of natural gravity flows of terrestrial surface materials mud lava salt and ice commonly express fast initial flux of the source followed by an exponential decline of the source strength flows having initially higher rk but otherwise equal life cycles create broader plumes peaks in the source flux due to magmatic pulsing during the eruption cycle can explain the formation of pillow lavas rather than instantaneously reaching full strength before declining some natural source flows start by swelling slowly leading to the creation of unique plume shapes like a flying saucer

processes controlling water and hydrocarbon composition in seeps from the salton sea geothermal system california usa water mud gas and petroleum bearing seeps are part of the salton sea geothermal system ssgs in southern california seeps in the davis schrimpf seep fi eld 14 000 m 2 show considerable variations in water temperature ph density and solute content water rich springs have low densities 98 vol halogen geochemistry of the waters indicates that mixing of deep and shallow waters occurs and that near surface dissolution of halite may overprint the original fl uid compositions carbon isotopic analyses suggest that hydrocarbon seep gases have a thermogenic origin this hypothesis is supported by the presence of petroleum in a water dominated spring composed of 53 saturated compounds 35 aromatics and 12 polar compounds the abundance of polyaromatic hydrocarbons and immature biomarkers suggests a hydrothermal formation of the petroleum making the ssgs a relevant analogue to less accessible hydrothermal seep systems e g the guaymas basin in the gulf of california

astronomical forcing of contrasting rainfall changes in tropical south america between 12 400 and 8800 cal yr b p abstract today precipitation over tropical south america is largely controlled by the seasonal movements of the inter tropical convergence zone itcz during the summer the itcz is shifted southward due to the warming of the continent paleoclimate data from southeastern amazonia and the central andes indicate that these two areas evolved similarly during the last 30 000 yr however between 12 400 and 8800 cal yr b p eastern amazonia received substantial moisture whereas the bolivian altiplano was arid this suggests that the itcz during summer was then farther north than it is today

experimental and analytic modeling of piercement structures 1 piercement structures such as mud volcanoes hydrothermal vent complexes pockmarks and kimberlite pipes form during the release of pressurized fluids the goal of this work is to predict under which conditions piercement structures form from the insights gained by sand box experiments injecting compressed air through an inlet of width w at the base of a bed of glass beads of height h at an imposed critical velocity vf a fluidized zone consisting of a diverging cone like structure formed with morphological similarities to those observed in nature dimensional analysis showed that vf is correlated to the ratio of h over w in addition we derived an analytical model for vf which is compared to the experimental data the model consists of a force balance between the weight and the seepage forces imparted to the bed by the flowing gas the analytic model reproduces the observed correlation between vf and h w although a slight underestimate was obtained the results suggest that the gas particle seepage force is the main triggering factor for fluidization and that the commonly used proxy which the fluid pressure must equal or exceed the lithostatic weight needs to be reconsidered by combining the experiments and the model we derived critical pressure estimates which were employed to a variety of geological environments comparing the estimated and measured pressures prior to the lusi mud volcano shows that the presented model overestimates the critical pressures the model paves the way for further investigations of the critical conditions for fluidization in earth systems

the lusi drone a multidisciplinary tool to access extreme environments abstract extreme and inaccessible environments are a new frontier that unmanned and remotely operated vehicles can today safely access and monitor the lusi mud eruption ne java island indonesia represents one of these harsh environments that are totally unreachable with traditional techniques here boiling mud is constantly spewed tens of meters in height and tall gas clouds surround the 100 m wide active crater the crater is surrounded by a 600 m diameter circular zone of hot mud that prevents any approach to investigate and sample the eruption site in order to access this active crater we designed and assembled a multipurpose drone the lusi drone is equipped with numerous airborne devices suitable for use on board of other multicopters during the missions three cameras can complete 1 video survey 2 high resolution photogrammetry of desired and preselected polygons and 3 thermal photogrammetry surveys with infra red camera to locate hot fluids seepage areas or faulted zones crater sampling and monitoring operations can be pre planned with a flight software and the pilot is required only for take off and landing a winch allows the deployment of gas mud and water samplers and contact thermometers to be operated with no risk for the aircraft during the winch operations that can be performed automatically the aircraft hovers at a safety height until the tasks controlled by the winch embedded processor are completed the drone is also equipped with gps connected co2 and ch4 sensors gridded surveys using these devices allowed obtaining 2d maps of the concentration and distribution of various gasses over the area covered by the flight path the device is solid stable even with significant wind affordable and easy to transport the lusi drone successfully operated during several expeditions at the ongoing active lusi eruption site and proved to be an excellent tool to study other harsh or unreachable sites where operations with more conventional methods are too expensive dangerous or simply impossible

younger dryas in southernmost south america an update abstract high resolution pollen data from a peat section in southern tierra del fuego documents high paleoenvironmental variability between 11 ka and 9 ka detailed analysis of plant macro remains in the same section showed that the repeated high amplitude changes in pollen taxa were related to repeated fire disturbance burning at least once even the surface of the mire in many peat sections from southernmost patagonia and tierra del fuego charcoal particles have been found intermittently since about 13 ka and in great abundance especially after 11 ka this suggests that the environmental changes previously interpreted to imply a return to colder climates comparable to the north atlantic younger dryas event instead are in response to local and regional disturbances by fires

climatic change during the younger dryas chron in northern south america a test of the evidence abstract new ams and palynological data are presented from the colombian andes to assess vegetational and climatic change during the lateglacial holocene transition with special emphasis on the younger dryas yd chronozone the new evidence is compared and discussed with other colombian cores and with data from other countries in the region the lateglacial climatic reversal in colombia known as the el abra stadial has an estimated lower boundary of 11 200 conventional and 10 900 interpolated 14 c yr bp respectively although the el abra stadial is assumed to be the equivalent of the european yd the present data suggest that the el abra stadial is a biostratigraphical signal representing both the yd chronozone and the earliest holocene 11 000 9000 14 c yr bp on the basis of new ams dates and a re evaluation of the pollen zones we divided the colombian el abra biozone into two phases from ca 11 000 to ca 10 500 14 c yr bp there is a sharp increase of subparamo and paramo pollen reflecting a relatively cool phase during the yd chronozone zone y1 after ca 10 500 14 c yr bp a slight increase of arboreal pollen and the presence of cactaceae zone z1 point toward a relatively milder but drier phase extending to ca 9000 14 c yr bp in the earliest holocene our conclusions add detail to the concept of astronomical forcing of contrasting rainfall changes in northern south america between 12 400 and 8800 14 c yr bp we propose an environmental drought during the el abra biozone with subsequent erosion of the sediments deposited during that period as a major factor explaining the poor presence of yd evidence in northern south america we conclude that at hydrologically sensitive sites without a clear lithological change around 11 000 9000 14 c yr bp a hiatus during the yd chronozone can only be detected if other cores are available with bracketed time control we state that the start of the temperature decline in central america and northern south america is related to the global yd cooling event however much work is still required to understand the duration and amplitude of the climatic reversal during the yd chronozone in this part of the globe

the geochemistry and origin of the hydrothermal water erupted at lusi indonesia abstract the spectacular lusi mud eruption started in northeast java the 29th of may 2006 despite extensive research the origin of the erupted water remains elusive and poorly constrained here we present a comprehensive study of the geochemistry of lusi waters compared with those collected from surrounding areas all collected between 2006 and 2013 including data from mud volcanoes and volcano hosted hydrothermal springs within this broad context the geochemical characteristics of the fluids expelled in the lusi region suggest that we can classify the waters in three groups 1 meteoric waters expelled in cold springs and artesian wells 2 hydrothermal waters typically mixed with meteoric waters and 3 formation water from marine sediments altered by diagenetic processes such as clay mineral dehydration samples collected from the lusi crater are cl and na dominated up to 527 mm and 471 7 mm respectively similar to seawater indicating that altered sedimentary formation waters are predominant in this system in addition they are enriched in sr up to 808 4 m and other elements commonly associated with hydrothermal systems such as li up to 877 6 m compared to 26 m in seawater some of these elements are up to ten times enriched compared to seawater values high temperature fluid mineral interactions in the subsurface appear to have facilitated the transfer of li and other mobile elements into the fluids high temperature fluid mineral interaction reactions are also supported by si concentrations significantly higher compared to other sampled mud volcanoes in the island crater samples also show the highest 18o values 5 after correction for evaporation compared to 1 at the mv localities 87sr 86sr ratios vary between of 0 7077 and 0 7083 and seem to reflect a general mixture of fluids from clay mineral dehydration carbonate recrystallization alteration of volcanic rocks and hydrothermal imprint eight years of geochemical monitoring indicate that the composition of the deep sourced lusi fluids remain fairly constant through time thus our findings show that the lusi crater waters represent a regional geochemical anomaly and we suggest that a combination of high temperatures in the source region and fluid rock interactions with silicates and possibly carbonate rich lithologies can explain the data this is consistent with a model where the emitted gases migrate from a deep seated 4 km source region likely associated with the presence of hot igneous intrusions and or high t reactions related to the presence of neighbouring active volcanoes

irregular glacial interstadials recorded in a new greenland ice core the greenland ice sheet offers the most favourable conditions in the northern hemisphere for obtaining high resolution continuous time series of climate related parameters profiles of 18o 16o ratio along three previous deep greenland ice cores1 3 seemed to reveal irregular but well defined episodes of relatively mild climate conditions interstadials during the mid and late parts of the last glaciation but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate rather than artefacts due to disturbed stratification here we present results from a new deep ice core drilled at the summit of the greenland ice sheet where the depositional environ ment and the flow pattern of the ice are close to ideal for core recovery and analysis the results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt according to a preliminary timescale based on stratigraphic studies the interstadials lasted from 500 to 2 000 years and their irregular occurrence suggests complexity in the behaviour of the north atlantic ocean circulation

tropical climatic variation on the pacific slopes of the ecuadorian andes based on a 25 000 year pollen record from deep sea sediment core tri 163 31b marine sediments from 3 37 s 83 58 w yield a well dated pollen record of equatorial andean vegetation moderate development of podocarpus high montane rainforest 34 000 28 000 yr b p and increase of high andean grassland pollen 28 000 16 000 yr b p imply an extended dry cool glacial period following a brief interstade rapid stepwise expansion in coastal and montane forest pollen characterizes the deglacial interval the general correspondence between pollen and oxygen isotope variations in tri 163 31b suggests that tropical climatic variations in the northern andes were basically coherent with northern hemisphere glacier variations

paleoenvironments and human occupation in late glacial panama the first pollen and phytolith data covering the entire pleistocene holocene transition from the lowlands of the central american isthmus indicate that the forests of late glacial panama at an altitude of 650 m resembled those currently found at ca 1500 1800 m a temperature depression of ca 5 c and reduced precipitation evaporation ratios in the late glacial period are suggested forest composition from ca 14 000 to 10 500 yr b p although primarily montane in character contained a low biomass of species today segregated in lowland forests and hence a floral assemblage with no modern analog the sudden appearance of carbon and burnt weedy plant material at ca 11 000 yr b p is attributed to the earliest human impact yet recorded from tropical america and may perhaps have been associated with the first human occupation of the region

exploration of geothermal systems using hyperspectral thermal infrared remote sensing abstract visible near infrared vnir short wave infrared swir and thermal infrared tir remote sensing has long been used for geothermal exploration specific focus on the tir region 8 12 m has resulted in major rock forming mineral classes being identified and their areal percentages to be more easily mapped due in part to the linear mixing behavior of tir emission to understand the mineral compositional and thermal distribution of active geothermal surfaces systems hyperspectral tir data from the spatially enhanced broadband array spectrograph system sebass airborne sensor were acquired over the salton sea ca geothermal fields by the aerospace corporation on march 26 2009 and april 6 2010 sebass collects 128 wavelength channels at 1 m spatial resolution such high resolution data are rarely available for this type of scientific analysis and enabled the identification of rare mineral assemblages associated with the geothermally active areas one surface unit with a unique spectrum believed to be a magnesium sulfate of unknown hydration state was identified for the first time in the sebass data the abundance and distribution of this mineral varied between 2009 and 2010 likely due to the precipitation conditions data obtained by the sebass sensor were also regressed to the 32 channel spectral resolution of the mineral and gas identifier magi airborne sensor in order to test sensitivity limits at this lower spectral resolution all surface minerals were still effectively identified and therefore validated data at magi resolution are still very effective for accurate surface compositional mapping a similar approach used at active geothermal areas in other semi arid regions around the world has the potential to better characterize transient mineralogy identify indicators minerals understand the influence of surface and ground water and ultimately to locate new geothermal targets for future exploration furthermore new mineral and gas identification magi data serve as an excellent precursor for future spaceborne tir data such as the system proposed for the hyperspectral infrared imager hyspiri instrument

lateglacial landscape and vegetation change and the younger dryas climatic oscillation in new zealand abstract lateglacial sequences in new zealand show progressive afforestation and landscape stabilization reflecting a warming climate between 14 500 bp and 11 500 bp afforestation and landscape stability was achieved throughout most of the north island and the northwest sector of the south island in the south island scrub and tree ferns were replacing previous grasslands in the east by 11 000 bp and broadleaved forest was spreading in the west no significant reversals of these trends occurred and afforestation was complete by 9500 bp glaciers of the high central part of the southern alps made a series of advances between 14 000 and 9000 bp most of these advances are poorly dated but two moraines are of younger dryas age glacial advances in the face of the general lateglacial warming trend may have been driven by stronger westerly winds increasing snowfall on high altitude neves and by reduced ablation as a consequence of moist cloudy low insolation summers the cause of the northern hemisphere younger dryas cooling is still uncertain and expected southern hemisphere responses may differ according to the mechanism proposed for the cooling poor chronological resolution and apparent conflict between the various types of evidence for climatic change make detection of an unambiguous younger dryas in new zealand problematical

the evaporation path of seawater and the coprecipitation of br and k with halite brines and salt were sampled at the morton bahamas solar salt production facility on great inagua island in the bahamas the brines were analyzed by ion chromatography to define more precisely than heretofore the evaporation path of seawater to the end of the halite facies at inagua calcium carbonate begins to precipitate at a brine concentration factor of 1 8 times that of seawater gypsum begins to precipitate at a brine concentration of 3 8 times seawater and halite at a concentration factor of 10 6 three of the most concentrated brines from inagua 40 times seawater were evaporated further in the laboratory magnesium sulfate first precipitated at brine concentrations about 70 times those of seawater and potassium bearing phases began to precipitate for these brines at concentrations greater than 90 times those of seawater the distribution of coefficients of br and k between brines and halite were determined by combining analytical data for the inagua brines with measurements of the br and k content of halites from inagua and of halite which had precipitated from inagua brines during storage the observed average value of dbr is 0 032 in good agreement with some of the previous measurements the measured values of dk are highly variable 0 001 to 0 021 dk for halite precipitated early in the halite facies is in the vicinity of 0 015

the wister mud pot lineament southeastward extension or abandoned strand of the san andreas fault we present the results of a survey of mud pots in the wister unit of the imperial wildlife area thirty three mud pots pot clusters or related geothermal vents hundreds of pots in all were identified and most were found to cluster along a northwest trending line that is more or less coincident with the postulated sand hills fault an extrapolation of the trace of the san andreas fault southeastward from its accepted terminus north of bombay beach very nearly coincides with the mud pot lineament and may represent a surface manifestation of the san andreas fault southeast of the salton sea additionally a recent survey of vents near mullet island in the salton sea revealed eight areas along a northwest striking line where gas was bubbling up through the water and in two cases hot mud and water were being violently ejected

bubble mobility in mud and magmatic volcanoes the rheology of particle laden fluids with a yield stress such as mud or crystal rich magmas controls the mobility of bubbles both the size needed to overcome the yield stress and their rise speed we experimentally measured the velocities of bubbles and rigid spheres in mud sampled from the davis schrimpf mud volcanoes adjacent to the salton sea southern california combined with previous measurements in the polymer gel carbopol we obtained an empirical model for the drag coefficient and bounded the conditions under which bubbles overcome the yield stress yield stresses typical of mud and basaltic magmas with sub mm particles can immobilize millimeter to centimeter sized bubbles at stromboli volcano italy a vertical yield stress gradient in the shallow conduit may immobilize bubbles with diameter