reactive transport modelling of reflux dolomitization in the arab d reservoir ghawar field saudi arabia it has long been recognized that the arab d reservoir in ghawar field has been significantly dolomitized and that the distribution of dolomites is highly heterogeneous across this reservoir previous studies indicated that dolomite occurs with either a stratigraphic or non stratigraphic distribution when mapped dolomite tends to form several parallel linear trends across the field although stratigraphic dolomite was suggested to be formed early from highly evaporated pore fluids sourced from overlying evaporite deposits non stratigraphic dolomite was thought to be generated primarily from hydrothermal fluids sourced from below this study focuses primarily on these non stratigraphic dolomites and proposes that i these dolomites initially formed via seepage reflux but were reinforced by late stage hydrothermal dolomitization and ii reflux is also responsible for the formation of parallel linear trends of dolomite the reflux model hypothesizes that an evaporative lagoon which is the source of dolomitizing fluids formed during the falling stage systems tract of a depositional sequence and that with continuing sea level fall this lagoon migrated progressively towards deeper parts of an intrashelf basin adjacent to the ghawar field leaving behind lines of dolomite bodies along a series of temporary coastlines two dimensional reactive transport models have been built to test this hypothesis and have resulted in a predicted pattern of dolomite bodies that agrees with both the observed vertical distribution of non stratigraphic dolomite as well as the mapped lateral distribution of the dolomite trends in addition the major ion compositions of late jurassic seawater are calculated based on fluid inclusion data in the literature using jurassic seawater in current models leads to the absence of anhydrite cements and less potential of over dolomitization than using modern seawater

exogenous and endogenous growth of the unzen lava dome examined by satellite infrared image analysis abstract phase 1 of the most recent eruption of unzen volcano japan occurred between 1991 and 1993 and involved the endogenous and exogenous addition of magma to a growing summit lava dome the temporal variation between endogenous and exogenous styles of dome growth has an important bearing on the hazard posed by dome collapse and explosive events however such data are difficult to acquire and have previously only been obtained in a fully quantitative manner for the mount st helens dome in that case using detailed photogrammetry here we investigate these competing dome growth processes at unzen via analysis of their thermal emission signals present in shortwave infrared swir satellite imagery we find that both the endogenous and exogenous growth styles exhibit identifiable swir signatures whose magnitude can be related to their respective magma supply rates we find that the swir radiant area corresponding to endogenous growth is around four times larger than that corresponding to exogenous growth at the same magma discharge rate analysis of time series imagery indicates that like mount st helens unzen experienced a temporally decreasing magma discharge rate during phase 1 as time progressed and the discharge rate fell the growth style of the unzen dome changed from exogenous only through exogenous decreasing and endogenous increasing to endogenous only thus relative growth rates at the endogenous and exogenous areas of the unzen dome appear to be at least partly controlled by the overall magma discharge rate as with mount st helens the cause of this relationship was most likely the formation and strengthening of a brittle crust at the surface vent which impeded exogenous growth more effectively as time elapsed and the discharge rate fell these results suggest the similarity of the processes operating at the unzen and mount st helens domes though important differences remain in that dome growth was basically continuous at unzen whilst at mount st helens growth episodes were interspersed by significant periods of repose

an airborne real aperture radar study of the chesapeake bay outflow plume an airborne real aperture radar rar has been used to study the fronts associated with the chesapeake bay outflow plume during spring outflow conditions the rar produced images of the ocean surface with a range resolution of 10 m an azimuthal resolution of approximately 30 m and an image size of 2 5 km 24 km two sampling strategies were utilized one to synoptically map the entire mouth of the chesapeake bay at roughly hourly intervals and a second to capture the rapid evolution of particular features in addition flight times were chosen such that over the course of the entire experiment data were collected over all phases of the semidiurnal tidal cycle three distinct frontal signatures were observed in the imagery a primary front extended from inside the estuary along the chesapeake channel to an anticyclonic turning region east of cape henry and then extended southward along the coast toward cape hatteras this is the classic expression of the plume front inertial turning region and coastal jet a second front with a north south orientation was observed approximately 20 km east of the bay mouth this secondary front appears to mark the residual offshore density gradient a third front was identified east and south of cape henry within 2 km of the coast this front appears to mark the inshore edge of the plume and has not been documented previously time sequences of the imagery indicate that when moving in a clockwise sense around the primary front the frontal translation speed varies systematically from 20 cm s in the northern section to 50 cm s in the south the position of the primary front and the locations and trajectories of small scale frontal cusps suggest that bathymetry may be both a significant determinant of the front location as well as a source of along front variability these observations are possible due to the airborne rar s ability to collect high frame rate image sequences a capability that is not shared by present space based radar systems

bed scale spatial patterns in dolomite abundance part ii effect of varied fluid chemistry flow rate precursor mineralogy temperature textural heterogeneity nucleation density and bed geometry

numerical models of fluid flow in carbonate platforms implications for dolomitization abstract the role of fluid flow in dolomitization is evaluated through hydrologic simulations designed to capture and test numerically the essential elements of some common dolomitization models a two dimensional finite difference code bethke 1985 was used to simulate single phase flow of variable salinity fluids driven by compaction convection and topography in carbonate platforms and adjacent basinal sediments a simple hydrostratigraphic model consisting of a platform reef complex surrounded by basin filling shale was constructed to examine the magnitude and direction of compaction flow during the initial phase of subsidence most pore fluids in the shale migrate to the surface at velocities less than 0 1 mm yr and basin derived fluids are focused into the reef from only a limited distance of 10 km relatively porous and permeable basinal limestones and sandstones may act as conduits for updip fluid flow into the platform reef complex magnesium mass balance constraints coupled with hydrologic simulations suggest that burial compaction is not an efficient mechanism for regional dolomitization two layer hydrostratigraphic models involving variable salinity fluids show that evaporation of seawater results in downward and seaward fluid migration the magnitude of flow is a function of fluid density even fluids at salinities marginally elevated above normal seawater values are capable of penetration several hundreds of meters into the underlying sediments albeit at rates of less than 1 cm yr paleohydrologic simulations coupled with thermodynamic arguments support that reflux of surface derived waters evaporated past gypsum saturation is a viable dolomitization mechanism calculations utilizing rates of mg mass flux show that dolomitization of large carbonate platforms 10 km3 by fluids below halite saturation requires millions of years of reflux driven flow p thermal convection of seawater through carbonate platforms has been simulated by varying the basal heat flow the thermal pump produces a convection cell in which lateral and vertical flow achieve rates of 75 0 and 13 0 mm yr respectively the potential for dolomitization is high because a large reservoir of mg seawater is tapped elevated temperatures drive fluids further into the stability field for dolomite and kinetic inhibition of dolomite nucleation and growth is decreased simulations of high frequency glacio eustatic sea level oscillations suggest that a dynamic hydrologic regime may be established a sea level fall of 2 m lasting for 10 000 yr can drive lateral flow at rates up to 0 15 m yr dolomitization is possible because marine waters migrate through the carbonate platform in response to gradients of hydraulic head created by eustatic sea level fluctuations

controls on reflux dolomitisation of epeiric scale ramps insights from reactive transport simulations of the mississippian madison formation montana and wyoming abstract prediction of the geometry and petrophysical properties of dolomite geobodies depends on understanding both the hydrological system supplying reactive fluids and the chemistry of these fluids however patterns are complicated by the non linear response of the diagenetic system to depositional texture which controls both fluid flux via permeability architecture and reaction rate via effective surface area this study explores interactions between extrinsic controls spatial distribution of brine composition and temperature and intrinsic controls permeability and reactivity using local and regional scale reactive transport models of sequential episodes of brine reflux that resulted in partial dolomitisation of the mississippian madison ramp inter well scale models show preferential early dolomitisation of fine grained more reactive beds pervasive dolomitisation can occur most readily beneath the brine pool where flow is perpendicular to bedding and is most rapid at high brine fluxes down dip of the brine pool bedding parallel flow is focused in relatively permeable coarse grained beds providing reactants for strongly preferential alteration of intervening more reactive fine grained beds in contrast thicker sequences of fine grained beds dolomitise more slowly limited by the rate of supply of magnesium regional scale models with injection of brines of increasing salinity towards the ramp interior reproduce the observed pattern of dolomitisation however more realistic simulations in which reflux is driven by lateral density contrasts generate flow rates orders of magnitude too low for significant dolomitisation simulations suggest pervasive dolomitisation of epeiric scale ramps by a platform wide reflux circulation as often invoked is not feasible rather dolomitisation of such extensive systems critically requires local scale flow systems such as may result from topographically controlled variations in restriction of platform top seawater circulation

discrimination of lava dome activity styles using satellite derived thermal structures abstract thermal imaging from satellites is one methodology used for the monitoring and scientific investigation of volcanoes including those characterised by active lava domes to be most effective the remote sensing techniques employed must allow the cause of any observed thermal anomaly to be identified ideally using information contained within the remote sensing data itself whilst using any ancillary field data to guide analysis and the necessary assumptions this study investigates a method by which such discrimination maybe accomplished for activity at lava domes for this purpose we use three landsat thematic mapper tm scenes of unzen volcano japan to determine the temperature structure of the active lava dome existing during 1991 1993 these data are of particularly high quality since the tm scenes were obtained during night time overpasses and a large amount of supplementary data are available to parameterise the model used to retrieve the subpixel temperature structure of the dome surface the results are matched to near contemporaneous geological sketch maps of the then current situation in order to identify the tm pixel groupings corresponding to the different styles of dome activity namely fumarolic degassing exogenous and endogenous dome growth and collapse deposits resulting from block and ash flows small scale pyroclastic flows and rockfalls the spatial and statistical characteristics of the resultant tm derived temperature distributions are then investigated to determine rule based criteria that may be used to differentiate the activity styles of lava domes based on their thermal structure within the remote sensing data results indicate that fumarolically active locations regions of active dome growth and areas of collapse deposition on the unzen dome can be differentiated using only the statistical distribution of the hotspot temperatures and fractional areas identified via analysis of tm imagery the statistics derived for hotspots at the fumarolically active areas show them to be in general significantly hotter and smaller than those found at the areas of active dome growth whereas hotspots retrieved on the areas of collapse deposition are cooler and larger we find that the frequency distributions of hotspot temperatures extracted for the areas of endogenous and exogenous dome growth exhibit statistically inseparable means but that discrimination between these two dome growth styles is possible using analysis of the spatial arrangement of the retrieved hotspots specifically the exogenous lobes are characterised by structures interpreted to be the effusing vent of new magma and the collapsing lobe front these features are absent at locations showing only endogenous growth it is hoped that the criteria developed here will prove useful during future quantitative analysis of the extended tm time series available for unzen and for identification of thermal anomalies of uncertain origin at other active domes observed via satellite remote sensing

an overview of the 2009 eruption of redoubt volcano alaska abstract in march 2009 redoubt volcano alaska erupted for the first time since 1990 explosions ejected plumes that disrupted international and domestic airspace sent lahars more than 35 km down the drift river to the coast and resulted in tephra fall on communities over 100 km away geodetic data suggest that magma began to ascend slowly from deep in the crust and reached mid to shallow crustal levels as early as may 2008 heat flux at the volcano during the precursory phase melted 4 of the drift glacier atop redoubt s summit petrologic data indicate the deeply sourced magma low silica andesite temporarily arrested at 9 11 km and or at 4 6 km depth where it encountered and mixed with segregated stored high silica andesite bodies the two magma compositions mixed to form intermediate silica andesite and all three magma types erupted during the earliest 2009 events only intermediate and high silica andesites were produced throughout the explosive and effusive phases of the eruption the explosive phase began with a phreatic explosion followed by a seismic swarm which signaled the start of lava effusion on march 22 shortly prior to the first magmatic explosion early on march 23 2009 utc more than 19 explosions or events were produced over 13 days from a single vent immediately south of the 1989 90 lava domes during that period multiple small pyroclastic density currents flowed primarily to the north and into glacial ravines three major lahars flooded the drift river terminal over 35 km down river on the coast tephra fall deposited on all aspects of the edifice and on several communities north and east of the volcano and at least two and possibly three lava domes were emplaced lightning accompanied almost all the explosions a shift in the eruptive character took place following event 9 on march 27 in terms of infrasound signal onsets the character of repeating earthquakes and the nature of tephra ejecta more than nine additional explosions occurred in the next two days followed by a hiatus in explosive activity between march 29 and april 4 during this hiatus effusion of a lava dome occurred whose growth slowed on or around april 2 the final explosion pulverized the very poorly vesicular dome on april 4 and was immediately followed by the extrusion of the final dome that ceased growing by july 1 2009 and reached 72 m m 3 in bulk volume the dome remains as of this writing effusion of the final dome in the first month produced blocky intermediate to high silica andesite lava which then expanded by means of lava injection beneath a fracturing and annealing cooling surface crust in the first week of may a seismic swarm accompanied extrusion of an intermediate to high silica andesite from the apex of the dome that was highly vesicular and characterized by lower p 2 o 5 content the dome remained stable throughout its growth period likely due to combined factors that include an emptied conduit system steady degassing through coalesced vesicles in the effusing lava and a large crater pit created by the previous explosions we estimate the total volume of erupted material from the 2009 eruption to be between 80 m and 120 m m 3 dense rock equivalent dre the aim of this report is to synthesize the results from various datasets gathered both during the eruption and retrospectively and which are represented by the papers in this publication we therefore provide an overall view of the 2009 eruption and an introduction to this special issue publication

origin of dolomite in the third member of feixianguan formation lower triassic in the jiannan area sichuan basin china abstract the third member of feixianguan formation jiannan area consists of marine carbonates parts of which were dolomitized to form high quality reservoirs based on petrographical features three types of dolomite phases are distinguished including very finely finely crystalline dolomite type d1 medium crystalline dolomite type d2 and coarse crystalline saddle dolomite type d3 type d1 dolomite has characteristics of micritic to fine crystals 18 o values imply partly diagenetic stabilitization during burial type d2 dolomite has characteristics of mainly medium 100 250 m subhedral crystals with zoned to uniform dull red cl the estimates from 18 o values suggest precipitation at depths of 760 1100 m values of 13 c and 87 sr 86 sr of type d2 are similar to values of host limestone suggesting that dolomitization was mediated by t 1 f 3 seawater like fluids type d3 is strictly associated with type d2 high homogenization temperatures and limited distributions indicate that type d3 formed in a deep closed environment dolostone made of type d1 dolomite is volumetrically minor and is characterized by micropores and low permeability while type d3 as a void filling cement slightly reduces the reservoir porosity high quality reservoirs are only intimately associated with dolostone made of type d2 a burial compaction model is proposed for type d2 mg 2 was derived from seawater derived compaction fluid that was expelled from the trough strata the potential high quality reservoirs are likely to occur in opposing margin shoals

remote observations of eruptive clouds and surface thermal activity during the 2009 eruption of redoubt volcano abstract volcanoes often erupt explosively and generate a variety of hazards including volcanic ash clouds and gaseous plumes these clouds and plumes are a significant hazard to the aviation industry and the ground features can be a major hazard to local communities here we provide a chronology of the 2009 redoubt volcano eruption using frequent low spatial resolution thermal infrared tir mid infrared mir and ultraviolet uv satellite remote sensing data the first explosion of the 2009 eruption of redoubt volcano occurred on march 15 2009 utc and was followed by a series of magmatic explosive events starting on march 23 utc from march 23 april 4 2009 satellites imaged at least 19 separate explosive events that sent ash clouds up to 18 km above sea level asl that dispersed ash across the cook inlet region in this manuscript we provide an overview of the ash clouds and plumes from the 19 explosive events detailing their cloud top heights and discussing the variations in infrared absorption signals we show that the timing of the tir data relative to the event end time was critical for inferring the tir derived height and true cloud top height the ash clouds were high in water content likely in the form of ice which masked the negative tir brightness temperature difference btd signal typically used for volcanic ash detection the analysis shown here illustrates the utility of remote sensing data during volcanic crises to measure critical real time parameters such as cloud top heights changes in ground based thermal activity and plume cloud location

the interaction of tectonics climate and eustasy in controlling dolomitization a case study of cenomanian turonian shallow marine carbonates of the iberian basin

application of the trace element and isotope geochemistry of strontium to studies of carbonate diagenesis carbonate rocks and natural waters exhibit a wide range in the concentration and isotopic composition of strontium this wide range and the quantifiable covariation of these parameters can provide diagnostic tools for understanding processes of fluid rock interaction careful consideration of the uncertainties associated with trace element partitioning sample heterogeneity and fluid rock interaction mechanisms is required to advance the application of the trace element and isotope geochemistry of strontium to studies of diagenesis goundwater evolution ancient seawater chemistry and isotope stratigraphy a principal uncertainty involved in the application of sr concentration variations to carbonate systems is the large range of experimental and empirical results for trace element partitioning of sr between mineral and solution this variation may be a function of precipitation rate mineral stoichiometry crystal growth mechanism fluid composition and temperature calcite and dolomite in ancient limestones commonly have significantly lower sr concentrations 20 70 p p m than would be expected from published trace element distribution coefficient values and sr ca ratios of most modern sedimentary pore waters this discrepancy probably reflects the uncertainties associated with determining distribution coefficient values as techniques improve for the analytical measurement and theoretical modelling of sr concentration and isotopic variations the petrological analysis of carbonate samples becomes increasingly important the presence of even small percentages of non carbonate phases with high rb concentrations and high 87 sr86 sr values such as clay minerals can have significant effects on the measured 87 sr 86 sr values of carbonate rocks due to the decay of 87rb to 87 sr for example a permian marine limestone with 50 p p m sr and 1 p p m rb will have a present day 87 sr 86 sr value that is 2 10 4 higher than its original value this difference is an order of magnitude greater than the analytical uncertainty and illustrates the importance of assessing the need for and accuracy of such corrections a quantitative evaluation of the effects of water rock interaction on sr concentrations and isotope compositions in carbonates strengthens the application of these geochemical tracers geochemical modelling that combines the use of trace elements and isotopes can be used to distinguish between different mechanisms of water rock interaction including diffusive and advective transport of diagenetic constituents in meteoric pore fluids during the recrystallization of carbonate minerals quantitative modelling may also be used to construct diagnostic fluid rock interaction trends that are independent of distribution coefficient values and to distinguish between mixing of mineral end members and fluid rock interaction

pore networks in holocene carbonate sediments abstract permeabilities of holocene carbonate sediments from florida and the bahamas determined for 74 samples by water flow rates in a variable head permeameter range from 0 6 to 57 000 millidarcies porosities range from 40 to 78 percent these parameters are related to depositional texture as follows table the muddiest sediments i e the finest grained have the highest porosities but lowest permeabilities this negative correlation between porosity and permeability is the reverse of the situation found in carbonate rocks even as young as pleistocene high porosity and low permeability in sediments show a strong correlation with percentage of fines 62 m from capillary pressure curves it is inferred that many of the pore throats of muddy carbonate sediments are less than 1 m in diameter at least after drying measured permeabilities are used to calculate cementation rates for simple models of upper phreatic zone cementation the calculated rates would require excessive time to produce the degree of cementation seen in late pleistocene rocks of florida and the bahamas the amounts of rainfall and evaporation are the most important factors in the degree of cementation

temporal trends in lava dome extrusion at santiaguito 1922 2000 we present a means of extracting lava dome extrusion rates from data provided by the thematic mapper and enhanced thematic mapper plus instruments flown on the landsat satellites extrusion rates derived from the landsat data for santiaguito dome complex guatemala during november 1987 and january 2000 of 0 72 0 08 and 0 48 0 09 m3 s 1 compare favorably with ground based estimates of 0 63 0 28 and 0 48 0 17 m3 s 1 a satellite data derived set of 18 extrusion rate estimates between 1987 and 2000 along with ground based volume estimates prior to 1987 allow us to infer volumes of magma erupted since 1922 these data reveal cyclic extrusion at santiaguito each cycle begins with a 3 6 year long phase of high extrusion rate 0 5 2 1 m3 s 1 followed by a longer 3 11 years phase of low extrusion rate 0 2 m3 s 1 the 8th cycle began in 1996 and was still in its high extrusion rate phase during january 2000 with time however the durations of the low extrusion rate phases have increased peak extrusion and time averaged extrusion rates for each cycle have decreased and the difference between extrusion rates during the high and low extrusion rate phases of each cycle has decreased these trends may be the result of depressurization and exhaustion of the source in this case the current eruption may be expected to end around 2020 alternatively santiaguito may be entering a period of persistent activity maintained by a stable magma supply in this case we may expect extrusion to become less cyclic and to stabilize at 0 2 0 4 m3 s 1 however a 2 wt decrease in sio2 content of erupted products since 1970 appears to be consistent with chamber exhaustion as well as an increase in block lava flow lengths during 1970 2000

geothermal convection in the tengiz carbonate platform kazakhstan reactive transport models of diagenesis and reservoir quality a fundamental challenge in carbonate reservoir characterization is predicting the spatial distribution of diagenesis we used a reactive transport model to investigate the viability of geothermal convection and associated patterns of diagenetic porosity modification in the tengiz isolated carbonate platform reservoir before burial forced convection generates significant calcite dissolution locally up to 45 toward the platform center minor calcite cementation up to 0 4 in the slope and moderate calcite dissolution and cementation up to 1 6 in serpukhovian boundstone convective cells the patterns and rates of diagenesis proved critically sensitive to specified vertical permeability after burial with 200 m 660 ft of salt modeled subsurface temperature contrasts drive platform scale free convection flow is hydraulically closed but significant dissolution up to 7 3 after 20 m y occurred in the serpukhovian and visean platform interior and minor cementation up to 0 7 occurred toward the margin a shale filled salt withdrawal basin 500 m 1640 ft deep significantly modifies the subsurface temperature distribution and free convective flow ascending groundwaters beneath the withdrawal basin created a zone of calcite dissolution up to 24 5 in 20 m y with a mushroom geometry and minor cementation up to 2 3 in 20 m y in the distal platform interior and margin rates of diagenesis are dramatically reduced with increasing overburden as compaction retards convective flow from a generic perspective free convection persists if the salt overburden is substituted with shale although flow is reversed resulting in a different distribution of diagenesis simulations of geothermal convection provide a physically viable model for the integration of direct diagenetic observations to augment predictions of reservoir quality in tengiz and other carbonate platform reservoirs

spatial patterns of diagenesis during geothermal circulation in carbonate platforms geothermal convection of seawater deep in carbonate platforms could provide the necessary supply of magnesium for dolomitization at temperatures high enough to overcome kinetic limitations we used reactive transport simulations to predict the rates and spatial patterns of dolomitization during geothermal convection in a platform that was 40 km across and 2 km thick in the simulations porosity and permeability decrease with depth to account for sediment compaction dolomitization of a platform consisting of medium grained 0 0 5 mm sediments occurred in a broad band ranging from 2 5 km depth near the margin to 1 5 km depth near the platform center the area of dolomitization is deep enough that temperatures exceed 50 c but not so deep that low permeabilities restrict mass transport complete dolomitization in the center of this zone is estimated to require at least 60 my incorporation of permeability contrasts permeable beds and reactive beds focused dolomitization strongly and reduced the estimated time required for dolomitization by as much as 50 percent dolomitization created magnesium depleted calcium rich fluids in less than 10 ky and results support a link between dolomitization and anhydrite precipitation where adequate sulfate is available

integrated characterization of carbonate ramp reservoirs using permian san andres formation outcrop analogs the san andres formation permian guadalupian of the permian basin is representative of carbonate ramp reservoirs in that it has highly stratified character complex facies and permeability structure and generally low recovery efficiencies of 30 of original oil in place the approach used here to describe carbonate ramp reservoirs such as the san andres formation produces detailed reservoir models based on integration of sequence stratigraphic analysis petrophysical quantification through definition of rock fabric flow units and fluid flow simulation synthesis of these subdisciplines clarifies which aspects of the geologic petrophysical model are most significant in predicting reservoir performance and ultimately in understanding the location of remaining oil satur tion the san andres formation crops out along the algerita escarpment a long oblique dip continuous shelf to basin exposure in the central guadalupe mountains these outcrops provide a unique opportunity to study lateral relationships in geologic and petrophysical structure analogous to those occurring between wells in subsurface reservoirs on the basis of sequence stratigraphic analysis three scales of cyclicity are recognized depositional sequences high frequency sequences and cycles examination of the cycles in two detailed window areas provides a practical scale for petrophysical quantification and fluid flow simulation an understanding of cycle position within the high frequency sequence framework also provides predictive information petrophysical analysis revealed six rock fabric groups dominated by intergranular separate vug or dense intercrystalline pore types comparison of these rock fabric groups with facies descriptions produced a rock fabric flow unit model that honors the geologic structure of the cycle and sequence framework permeability data were averaged within rock fabric flow units using a geometric mean approach based on fine scale fluid flow modeling of deterministic and stochastically generated permeability fields two dimensional black oil fluid flow models illustrate that 1 major differences in sweep efficiency and fluid flow performance are predicted when linear interwell interpolations are compared with actual interwell scale geologic structure as determined by outcrop geologic and petrophysical mapping 2 an understanding of static geologic petrophysical conditions provides only a partial understanding of reservoir performance defined by the interaction of these static properties and dynamic properties of fluid flow interaction within the flow unit architecture and 3 because of the orderly distribution of high and low permeability facies within cycle stacks of high frequency sequences this larger scale of geologic description can give a reasonable first order approximation of fluid flow patterns and early breakthrough end page 181

eustatic control on early dolomitization of cyclic peritidal carbonates evidence from the early ordovician upper knox group appalachians the early ordovician upper knox group is characterized by stacked meter scale peritidal cycles that repeat at high frequencies 10 4 to 10 5 yr stacking patterns stratigraphic trends in lithofacies and cycle thickness of meter scale cycles define five depositional sequences that in conjunction with fischer plots delineate five long term relative sea level fluctuations during upper knox deposition intrabasinal and interbasinal correlation of upper knox fischer plots suggests that the third order sea level events were eustatic meter scale peritidal cycles likely formed in response to high frequency fourth and fifth order eustatic sea level fluctuations superimposed on these third order sea level events upper knox cyclic carbonates are extensively dolomitized as much as 85 of all dolomite is stratiform and consists of early dolomite exhibiting minor to extensive modification by burial dolomite synsedimentary dolomitization likely occurred in modified sea water during tidal flat progradation governed by high frequency sea level events this is suggested by the common association of dolomite with mud cracked laminites and silicified evaporite nodules the systematic decrease in dolomite abundance below laminite cycle caps and the presence of dolomite clasts in regoliths veneering high frequency cycle tops or in transgressive limestones of the overlying cycle dolomite distribution within depositional sequences shows a strong relationship to third and fourth order eustatic sea level events indicating that long term eustasy also strongly controlled early dolomitization of upper knox carbonates mass balance calculations show that the proposed sabkha model of dolomitization in concert with composite eustasy could generate stratiform dolomite of considerable vertical and lateral extent in peritidal cyclic carbonates this reflects the duration of progradation and supratidal exposure 10 4 to 10 5 yr available for dolomitization to proceed and the broad zone of active dolomitization that would develop during continued progradation throughout each cycle period

fate of reflux brines in carbonate platforms active reflux may occur during periods of platform top brine generation but the role and fate of these brines after reflux events are uncertain we have used a numerical flow model to investigate and quantify the response of reflux brines to changes in platform top salinity simulations suggest that reflux brines originally concentrated to gypsum saturation 150 have a relatively long platform residence time on the order of 100 times the duration of the reflux event when brine generating conditions cease brines will continue to sink through the platform entraining seawater a variant of reflux circulation we term latent reflux mesosaline brines intercepted by drilling of carbonate margins by the ocean drilling program may have originated from pleistocene reflux event s on the adjacent platform top and be currently moving by latent reflux latent reflux circulation could deliver a significant quantity of dissolved reactants to platform carbonates including mg for dolomitization

detection of a new summit crater on bezymianny volcano lava dome satellite and field based thermal data an explosive eruption occurred at the summit of bezymianny volcano kamchatka peninsula russia on 11 january 2005 which was initially detected from seismic observations by the kamchatka volcanic eruption response team kvert this prompted the acquisition of 17 advanced spaceborne thermal emission and reflection radiometer aster satellite images of the volcano over the following 10 months visible and infrared data from aster revealed significant changes to the morphology of the summit lava dome later seen with field based thermal infrared tir camera surveys in august 2005 the morphology of the summit lava dome was observed to have changed from previous year s observations and historical accounts in august 2005 the dome contained a new crater and two small lava lobes stepped scarps within the new summit crater suggest a partial collapse mechanism of formation rather than a purely explosive origin hot pyroclastic deposits were also observed to have pooled in the moat between the current lava dome and the 1956 crater wall the visual and thermal data revealed a complex eruption sequence of explosion s viscous lava extrusion and finally the formation of the collapse crater based on this sequence the conduit could have become blocked pressurized which could signify the start of a new behavioural phase for the volcano and lead to the potential of larger eruptions in the future

thermal distributions of hot volcanic surfaces constrained using three infrared bands of remote sensing data infrared remote sensing provides a means for radiometry of hot volcanic features previously two spectral band measurements have been combined to solve simple 2 component models of lava surface temperatures however pixel dimensions often exceed the widths of lava bodies in such cases 3 component models are more realistic here a procedure for solving such a model from three infrared observations is presented it is then demonstrated using thematic mapper simulator data recorded over mount etna italy in 1991 by constraining temperatures and pixel filling fractions of the three different thermal components in this way improved estimates of radiant emittance can be obtained the techniques described could be applied to satellite data of volcanic and other hot spots including fires

compaction and decompaction algorithms for sedimentary carbonates abstract the mechanical compaction behavior of shallow marine carbonate sediments has been investigated to develop carbonate compaction algorithms and decompaction curves that can be used in stratigraphic restoration backstripping analyses and quantitative models for simulation of carbonate stratigraphy deep water chalks and calcareous oozes are not treated here empirical porosity depth data for carbonate sediments have been compiled and compared with experimentally derived compaction curves to derive appropriate porosity depth curves for shallow water carbonate muds and sands the curves are exponential in form this review indicates that mud rich shallow marine carbonates behave differently than sand rich grain supported sediments with regard to reduction in porosity and thickness quantitative analysis of compaction behavior in carbonate sediments reveals that barring early cementation carbonate muds suffer significant thickness reduction early in their burial history and at shallow depths e g 50 thickness reduction with about 150 200 m overburden however primary porosities of carbonate muds approximately 70 80 are reduced only to about 42 under that overburden thus the potential exists for significant retention of primary porosity in carbonate muds in the form of microporosity this indicates that interparticle cementation with or without chemical compaction is required to transform muddy carbonate sediments into lithified rock in the absence of early lithification carbonate sands compact more slowly than muds primary interparticle porosities of about 40 45 can be maintained in the first 200 300 m of burial with little thickness reduction

surface river plume in a large lake under wind forcing observations and laboratory experiments abstract observations of a small riverine plume grand river on in the nearshore zones of lake erie were analyzed to describe its spatial variability and its thickness under different wind forcing conditions during late spring of 2012 observational results reveal a well marked frontal region in the vicinity of the river mouth causing the plume to discharge into the lake in the surface layers positive buoyant wind driven alongshore currents at the mid depth had speeds of 2 9 cm s in comparison to those in the cross shore 3 6 cm s which transported the plume along the shore during the measurement period series of laboratory experiments were conducted to obtain the propagation speed u of the buoyant plume in terms of buoyancy anomaly ba richardson number ri dimensionless time t and aspect ratio a based on our experiments we developed two non dimensional relationships describing the speed of propagation u as u ba 1 2 8 ri 1 2 t 1 3 a and the plume thickness h as h h 0 8 ri 1 4 t 1 2 a in the water depth h which are in agreement with field observations

wind driven motion near inner shelf fronts the response of inner shelf fronts to wind forcing is numerically studied here by using a three dimensional primitive equation model the front and its associated circulation are maintained by discharging light water near the surface and withdrawing heavier water from below along one vertical wall of a cyclic channel subsequently a spatially uniform alongshore wind is applied responses to an upwelling favorable wind and to a downwelling favorable wind are highly asymmetric upwelling favorable wind forces the light water pool to surface and expand offshore the pool is quickly detached from the source by the newly upwelled water even for a moderate plume and strong wind it is unlikely that a downwind coastal jet can develop and force the plume to turn against its natural direction of propagation recent observations of chesapeake plume support this finding downwelling favorable wind slowly narrows the plume inside which a strong coastal jet is developed for a density anomaly of finite alongshore extent the jet intensifies downstream reaches a maximum near the lead isopycnal and decays thereafter to compensate for the downstream acceleration strong onshore flow develops near the upstream edge of the plume if the wind persists the enhanced onshore flow further narrows the plume and triggers a second intrusion unstable waves develop behind the second intrusion they are however limited to small amplitudes by the prevailing onshore ekman drift

character mass distribution and origin of tephra fall deposits from the 2009 eruption of redoubt volcano alaska highlighting the significance of particle aggregation abstract the 2009 eruption of redoubt volcano included 20 tephra producing explosions between march 15 2009 and april 4 2009 utc next generation radar nexrad data show that plumes reached heights between 4 6 km and 19 km asl and were distributed downwind along nearly all azimuths of the volcano explosions lasted between 0 8 mm thick including communities along the kenai peninsula 80 100 km and the city of anchorage 170 km trace ash on march 15 a small 4 6 km asl phreatic explosion containing minor non juvenile ash erupted through the summit ice cap the first five magmatic explosions events 1 5 occurred within a 6 hour period on march 23 plumes rose to heights between 5 5 km and 14 9 km asl during 2 to 20 minute duration explosions and were dispersed mainly along a nne trajectory trace ash fall was reported as far as fairbanks owing to a shift in wind direction and heavy snowfall during these events field discrimination among many of these layers was possible all deposits comprise a volumetrically significant amount of particle aggregates yet only event 5 deposits contain coarse clasts including glacier ice the most voluminous tephra fall was deposited on march 24 event 6 from a 15 minute explosion that sent a plume to 18 3 km asl and dispersed tephra to the wnw within 10 km of the vent this deposit contains 1 11 cm pumice clasts in a matrix of 1 2 mm aggregate lapilli a small dome was presumably emplaced between march 23 and march 26 and was subsequently destroyed during 1 14 minute magmatic explosions of events 7 8 march 26 that sent plumes between 8 2 km and 19 km asl ash fell along a broad swath to the ese covering communities along the kenai peninsula with up to 1 mm of ash proximal deposits are largely composed of aggregate lapilli of 1 2 mm with very little coarse juvenile material events 9 18 march 27 sent plumes between 5 2 km and 15 5 km asl during particle size data showing a preponderance of fine ash even in the most proximal locations along with the abundance of aggregate lapilli documented in most samples confirms that particle aggregation played a significant role in the 2009 eruption and induced premature fallout of fine ash

effects of mineral composition and heterogeneity on the reservoir quality evolution with co2 intrusion during the diagenesis of rocks in a sedimentary basin an intrusion of co2 could cause dissolution or and precipitation of the surrounding rocks as a result the reservoir quality may be altered the mineral composition and heterogeneity have pronounced impacts on the geochemical reaction and reservoir quality evolution a numerical simulation method is employed to investigate the influences of primary mineral on the diagenesis based on the measured data from the songliao basin a total of 26 two dimensional models with different mineral composition are set up to mimic the regionally heterogeneous distribution of mineral composition the monte carlo method is employed a co2 gas reservoir of magma intrusion origin located in the songliao basin northeastern china is selected for the present study the reservoir is an ideal site for investigating the impact of mineral heterogeneity on diagenesis after the co2 intrusion in this reservoir with the presence of high pressure co2 the mineral heterogeneity causes significant dissolution and precipitation of minerals which decreases the reservoir porosity and degrades the reservoir quality the geochemical reactions caused by different mineral composition vary widely the mineral heterogeneity causes similar distributions of the geochemical reactions and reservoir quality evolution dominant secondary minerals are dawsonite in the early diagenesis and ankerite in the late stage the diagenetic sequences modeled by our numerical simulations reproduce the petrographic and geochemical data well

outcrop analog for cyclic shelf reservoirs san andres formation of permian basin stratigraphic framework permeability distribution geostatistics and fluid flow modeling vertical and horizontal transects were sampled from core and outcrop of the san andres formation at lawyer canyon guadalupe mountains new mexico to assess permeability variation in a geologic framework of upward shallowing carbonate cycles and to show the potential effect these variations have on viscous dominated flow behavior in analogous reservoirs these cycles occur in a ramp crest facies tract are 3 13 m 10 45 ft thick and contain both vertical and lateral variation of lithofacies thicker cycles consist of a basal dolomudstone which is overlain by burrowed dolopackstone and capped by bar flank ooid peloid dolograinstone and bar crest ooid dolograinstones in vertical transects permeability is extremely variable about the mean yet upward increasing trends coinciding with the succession of lithofacies typify a given cycle semi variance analysis shows permeability to be uncorrelated vertically at distances greater than 5 5 m 18 ft which is the average cycle thickness suggesting that the cycles may equate to a fluid flow unit in a reservoir semi variance analysis of measurements collected along a horizontal transect within bar crest dolograinstones of a single cycle shows permeability is uncorrelated at distances greater than 3 6 m 12 ft this correlation distance appears to be controlled by alternating porous and tightly cemented zones that formed during dolomitization vertical and lateral variogram models were fit to the spatial parameters to generate a variety of conditionally simulated permeability fields fluid flow simulations show viscous dominated flow behavior is compartmentalized by both the individual cycles and groups of cycles the basal dolomudstones are potential baffles to flow crossover between cycles but poorly developed cycles i e those that are mud rich and lack well developed bar flank and bar crest facies result in the greatest compartmentalization of fluid flow within a succession of cycles

formation of diagenetic dolomite in coastal sabkha along arabian persian gulf aragonitic intertidal sediments are being dolomitized in the subsurface supratidal environment of a sabkha along the south shore of the arabian persian gulf as a result of the percolation of wind driven marine derived brines the development of abundant diagenetic dolomite results from an optimum combination of high mmg mca ratio fluids a rapid flow rate which is related to the flooding frequency and sediment permeability and a shoreline configuration that maintains the proper conditions for a sufficient length of time strongly dolomitized areas are localized along the flanks of remnant channels and in the lee of islands that have been engulfed by the prograding sabkha the dolomitizing process takes about 1 000 to 1 500 years most diagenetic dolomite forms at the expense of primary aragonite according to the reaction mg 2caco3 arag rarr camg co3 2 ca dolomite forms under the following conditions a chloride concentration between 3 25 and 3 75 mcl kg b mmg mca greater than about 6 c ph between 6 3 and 6 9 d minimum pco2 of 10 2 to 10 3 atm e temperature between 25 and 40 c f saturation with respect to gypsum and g reducing environment in association with hydrogen sulfide other recent dolomite occurrences in the bahamas florida and bonaire are significantly different in terms of stratigraphy degree of lithification and evaporite mineral association from those in the arabian gulf

convergence and downwelling at a river plume front abstract the small scale structure of the circulation and hydrography at the frontal boundary of the connecticut river plume in long island sound has been resolved using a novel combination of instruments a towed acoustic doppler current profiler adcp and a rigid array of current meters and conductivity temperature sensors observations were made during the latter half of the eastward ebb tide when the river plume was well established and the front was moving to the west at approximately 0 3 m s 1 two across front transects revealed a horizontal convergence rate in the across front velocity components at 0 6 m of 0 05 0 1 s 1 this was associated with a salt induced horizontal density gradient of 10 2 kg m4 observations obtained during a period in which the towed adcp was caught in the zone of maximum surface convergence showed significant downwelling with a near surface maximum of 0 2 m s 1 vertical velocities of this magnitude are consistent with observed magnitudes of the convergence rate at 0 6

dolomitization anhydrite cementation and porosity evolution in a reflux system insights from reactive transport models significant volumes of world hydrocarbon reserves occur in dolostones and the majority of these reservoirs are interpreted to be of reflux origin we used a two dimensional numerical reactive transport model to investigate systematically the temporal and spatial distribution of replacement dolomitization dolomite cementation anhydrite cementation and porosity evolution in a reflux system we tested the sensitivity of reflux dolomitization to brine concentration mesohaline to near halite saturated brines near surface temperature flow rate porosity permeability feedback relationships reactive surface area and the effect of initial porosity permeability heterogeneity simulations support the contention that hypersaline reflux is capable of extensive pervasive dolomitization and that mesohaline reflux dolomitization is viable reflux generated a tabular dolomite body that is thickest close to the brine source and thins basinward incorporation of initial porosity and permeability heterogeneity resulted in a dolomite body with pronounced lateral fingers replacement dolomitization increased porosity up to 8 but postreplacement reflux resulted in the precipitation of minor dolomite cements overdolomitization anhydrite cements that were spatially and temporally associated with replacement dolomitization caused a significant porosity reduction of up to 25 simulated rates of replacement dolomitization by reflux are fast up to three orders of magnitude faster than seawater dolomitization the rate of dolomitization and anhydrite mineralization proved to be critically sensitive to the flow rate and the brine chemistry temperature and reactive surface area were important controls on the rate of dolomitization whereas the feedback relationship between porosity and permeability was a relatively moderate control our reactive transport models predict the general spatial and temporal trends in dolomite porosity and anhydrite observed in some major dolomite reservoirs

effects of a volcanic plume on thermal imaging data ground based thermal imaging is becoming an increasingly important tool for volcano surveillance however the impact of volcanic plumes on quantitative measurements of surface temperature has not been previously evaluated here we use a radiative transfer model to simulate gas primarily h2o and so2 and aerosol absorptions over the path between a thermal camera and a heat source on stromboli volcano italy a ftir spectrometer was used to quantify path amounts of gases likely to be encountered when making thermal measurements of the active craters we find that when using a camera sensitive from 7 5 to 13 mu m underestimates of similar to 400 k may be produced when viewing a source with an actual temperature of 1200 k cameras that operate between 3 and 5 mu m are somewhat less susceptible to these errors

a modeling study of tidally driven estuarine exchange through a narrow inlet onto a sloping shelf the circulation and particle transport through a narrow inlet kelvin number 0 5 and onto a sloping shelf are numerically examined using a three dimensional hydrodynamic model the model domain consists of an estuarine basin with vertical density stratification separated from a well mixed sloping shelf by a narrow inlet forcing is supplied by semidiurnal tides and buoyancy differential strong ebb flows resulting from this combined forcing transport estuarine water seaward through the inlet to form a radially spreading buoyant surface plume over the shelf a series of radial density fronts corresponding with the ebbing tidal outflow are found on the seaward side of the inlet mouth and are convergence zones for floating particles strong anticyclonic frontal flow advects particles around the boundary of the outflow plume particles released nearest the seaward side of the inlet mouth are able to enter the inlet at depth and remain while those particles released farther offshore rarely enter the inlet this result has clear implications for the shelf to estuary transport of pollutants or the larval phase of marine species asymmetric tidally induced eddies which appear on both sides of the inlet also contribute to the near field circulation calculations of gradient richardson number in the inlet show that regions susceptible to enhanced mixing occur during periods of maximum tidal velocities due to increased shear

influence of subtle paleo tectonics on facies and reservoir distribution in epeiric carbonates integrating stratigraphic analysis and modelling u muschelkalk sw germany abstract the middle triassic upper muschelkalk carbonate ramp deposits in sw germany provide an excellent laboratory scale analogue for vast epeiric basin fills such as in the middle east the upper muschelkalk and the entire mesozoic overburden in sw germany were deposited on a complex mosaic of three major differentially subsiding variscan paleo tectonic blocks the rhenohercynian saxothuringian and moldanubian subtly influencing the depositional facies pattern for long periods of time this study is based on detailed sedimentological logs of 41 boreholes and surface outcrop sections and 39 gamma ray logs lithofacies analysis and a 1 d and 2 d sequence stratigraphic analysis leading to a regional correlation integrating sequence architecture and marker beds using the subsurface 3d modelling tool petrel two nested geocellular reservoir models were generated i a basin scale 201 5 325 km lithofacies associations lfa model based on truncated gaussian simulation tgs ii a field scale 50 50 km lithofacies types lft model based on sequential indicator simulation sis the integrated 3d facies models reveal landward facies retrogradation with patchy isolated shoal bodies during the transgressive hemisequence and basinward facies progradation with well connected large shoals within the regressive hemisequence models combined with structural maps show the influence of large variscan block segments and smaller scale internal structural elements on the distribution and the size of reservoir analogues both shoal and dolomite bodies this relationship offers a new tool for exploration in epeiric carbonates using deep seated paleo tectonic patterns for the prediction of both hydrocarbon and geothermal reservoirs

factors affecting the accuracy of thermal imaging cameras in volcanology volcano observatories and researchers are recognizing the potential usefulness of thermal imaging cameras both before and during volcanic eruptions obvious applications include measurements of the surface temperatures of active lava domes and lava flows to determine the location of the most active parts of these potentially hazardous features if appropriate precautions are taken the new generation of thermal imaging cameras can be used to extract quantitative as well as qualitative information on volcanic activity for example they can be used to measure the temperature of lava on eruption and to reveal how the crust cools during flow emplacement this is important for the validation of lava flow models to ensure that meaningful temperatures are collected thermal imaging data must be corrected for instrumental errors emissivity of the surface being imaged atmospheric attenuation viewing angle and surface roughness controlled laboratory experiments have been undertaken to determine the emissivity of smooth and rough samples and the effects of viewing angle and to quantify the errors measured emissivities range from 0 973 0 002 for smooth samples of basalt and 0 984 0 004 for rough samples errors in emissivity corrected temperatures are within 15 c for lava at 1100 c variations from individual sensor receptors which provide individual pixel temperature data were found to be 0 6 and instrumental errors of the cameras used were 0 1 apparent temperatures were found to vary by less than the instrumental error for viewing angles up to 30 degrees from normal to lava and thereafter increased by 1 c per degree by increasing the apparent viewing distance of a small vent on mount etna from 1 5 to 30 m the maximum temperature is shown to decrease by 53 c due to integrated averaging of radiance over increased pixel areas at a viewing distance of 250 m the maximum temperature decreased by 200 c with a further 75 c decrease due to atmospheric attenuation for a relative humidity of 50 however errors in relative humidity measurements can lead to atmospheric attenuation correction inaccuracies up to 200 c at viewing distances of 1 km we show how temperatures measured using thermal imaging cameras can be corrected to give improved estimates of temperature distributions on the surface of active lava flows

the influence of wind forcing on the chesapeake bay buoyant coastal current observations of the buoyant coastal current that flows southward from chesapeake bay are used to describe how the thickness width and propagation speed vary in response to changes in the along shelf wind stress three basic regimes were observed depending on the strength of the wind for weak wind stresses from 0 02 to 0 02 pa the buoyant coastal current was relatively thin the front slope was not steep and the width was variable 1 20 km for moderate downwelling southward wind stresses 0 02 0 07 pa wind driven cross shelf advection steepened the front causing the plume to narrow and thicken for stronger downwelling wind stresses greater than 0 07 pa vertical mixing dominated bulk richardson numbers were approximately 0 25 isopycnals were nearly vertical and the plume front widened but the plume width did not change plume thickness and width were normalized by the theoretical plume scales in the absence of wind forcing normalized plume thickness increased linearly from 1 to 2 as downwelling wind stresses increased from 0 to 0 2 pa normalized plume widths were approximately 1 for downwelling wind stresses from 0 02 to 0 2 pa the observed along shelf propagation speed of the plume was roughly equal to the sum of the theoretical propagation speed and the wind driven along shelf flow

observations of the response of a buoyant estuarine plume to upwelling favorable winds 1 the response of the buoyant plume from the chesapeake bay to upwelling favorable winds and during conditions of low freshwater discharge is examined using an offshore array of bottom deployed acoustic doppler current profilers adcps as well as ancillary data during periods of northward upwelling favorable winds the observed response is strong offshore flow u 0 2 m s in a shallow layer of plume water and a rapid reversal of the near surface flow from the usual southward flow associated with inertial turning of the plume the offshore migration of the plume front is deduced from sequential arrivals at the various mooring locations the orientation of the plume front is approximately alongshore north south suggesting that the upwelling response is two dimensional a plume thickness calculated from the adcp data is relatively constant at about 4 m as the plume moves across the moorings the offshore propagation speed of the plume front of about 0 20 m s matched the advection speed predicted by ekman theory using the calculated plume layer thickness the mooring velocity profiles provide a view of the across plume structure in a reference frame fixed to the front this reveals a pattern of circulatory motion with sinking of plume and ambient water at the front and an ascending motion occurring inshore suggesting a recirculation between the seaward and inshore portions of the plume these results are consistent with recent model simulations of the response of a river plume during upwelling favorable winds

meteoric diagenesis and fluid rock interaction in the middle permian capitan backreef yates formation slaughter canyon new mexico this study examines the geochemical record of diagenesis in the middle permian yates shelf exposed in slaughter canyon new mexico this diagenetic history significantly modified lithologies depositional fabrics and pore systems early diagenesis was dominated during sea level highstands by marine cementation and reflux dolomitization and during sea level lowstands by meteoric cementation and stabilization the focus of this study this early diagenesis variably overprinted primary marine isotopic signatures potentially leading to erroneous chemostratigraphic correlations or paleoclimate reconstructions four correlative sections through one m scale cycle were analyzed for their and values they show significant 2 4 and variability in coeval texturally well preserved calcites the and values of marine cements brachiopods bulk carbonate micritic matrix and the first generation of meteoric spar from high to low values delineate an inverted j curve indicating the variable alteration of components by diagenetic fluids numerical models indicate that the observed stable isotope trend is most consistent with diagenetic alteration in a partially closed system by meteoric fluids mixed with a progressively diminishing contribution of recycled marine waters in the yates shelf marine cements provide a more robust primary isotopic record than micritic matrix however neither preserves primary seawater isotopic values furthermore common criteria used to diagenetically screen samples proved inadequate e g textural preservation staining luminescence depletion near sequence boundaries instead diagenetic resetting is resolved by analyzing multiple closely spaced independently correlated sections and by delineating trends between primary and later diagenetic components in populations of isotopic data

gravity current structure of the chesapeake bay outflow plume measurements made across the edge of the chesapeake bay outflow plume in september 1996 are examined for evidence of the frontal head structure expected for a buoyant gravity current shipboard acoustic doppler current profiler and hydrographic data from two distinct 2 hour long sets of frontal transects are analyzed one set of observations was acquired just south of the bay mouth near cape henry virginia during late flood tide in water depth of 8 m these measurements show a nearly steady frontal structure and a frontal head that is approximately 5 m deep and 20 m wide the second data set was acquired about 20 km southeast of the bay mouth where the plume bulges horizontally outward over the continental shelf these measurements show a 9 m deep frontal head in water depth of 18 m that ultimately dissipates during early flood tide in both sets of observations relative inflow of plume water into the frontal head is confined to a shallow surface layer estimated to be no more than about 2 m deep referenced to this layer frontal propagation is supercritical froude number greater than 1 also measured was an expected sinking motion of the order of 3 cm s along the front overall the results are consistent with previous measurements made across smaller buoyant plumes and in the laboratory and they are compatible with the use of fixed values of froude number and entrainment parameter in two layer plume models additional study of the plume front during ebb tide is recommended

emplacement of the final lava dome of the 2009 eruption of redoubt volcano alaska abstract after more than 8 months of precursory activity and over 20 explosions in 12 days redoubt volcano alaska began to extrude the fourth and final lava dome of the 2009 eruption on april 4 by july 1 the dome had filled the pre 2009 summit crater and ceased to grow by means of analysis and annotations of time lapse webcam imagery oblique image photogrammetry techniques and capture and analysis of forward looking infrared flir images we tracked the volume textural effusive style and temperature changes in near real time over the entire growth period of the dome the first month of growth april 4 may 4 produced blocky intermediate to high silica andesite lava 59 62 3 wt sio 2 that initially formed a round dome expanding by endogenous growth breaking the surface crust in radial fractures and annealing them with warmer fresh lava on or around may 1 more finely fragmented and scoriaceous andesite lava 59 8 62 2 wt sio 2 began to appear at the top of the dome coincident with increased seismicity and gas emissions the more scoriaceous lava spread radially over the dome surface while the dome continued to expand from endogenous growth and blocky lava was exposed on the margins and south side of the dome by mid june the upper scoriaceous lava had covered 36 of the dome surface area vesicularity of the upper scoriaceous lava range from 55 to 66 some of the highest vesicularity measurements recorded from a lava dome we suggest that the stability of the final lava dome primarily resulted from sufficient fracturing and clearing of the conduit by preceding explosions that allowed efficient degassing of the magma during effusion the dome was thus able to grow until it was large enough to exceed the magmastatic pressure in the chamber effectively shutting off the eruption

evidence of free convection in groundwater field based measurements beneath wind tidal flats free convection caused by salinity differences had not been conclusively detected or measured in the field a field experiment at wind tidal flats on padre island national seashore texas documents salinity driven free convection with both direct head and salinity data and indirect time lapse 3 d resistivity methods evaporative concentration of groundwater near the water table created unstable inverted density gradients reduced groundwater levels and reversed hydraulic gradients these factors allowed plumes or fingers of more saline denser fluid to flow downward into less dense fluid as observed in monitoring wells and 3 d surveys the development of density inversions can overcome the dissipating forces of dispersion and diffusion to create a sufficiently large unstable gradient to induce free convection the development of free convective flow of variable density fluids in groundwater can be detected and monitored through field techniques

dome growth and destruction during the 1989 1990 eruption of redoubt volcano abstract much of the six month long 1989 1990 eruption of redoubt volcano consisted of a dome growth and destructive phase in which 14 short lived viscous silicic andesite domes were emplaced and 13 subsequently destroyed the life span of an individual dome ranged from 3 to 21 days and volumes are estimated at 1 10 6 to 30 10 6 m 3 magma supply rates to the vent area averaged about 5 10 5 m 3 day for most of the dome building phase and ranged from a high of 2 2 10 6 m 3 per day initially to a low of 1 8 10 5 m 3 per day at the waning stages of the eruption the total volume of all domes is estimated to be about 90 10 6 m 3 and may represent as much as 60 70 of the volume for the entire eruption the site of 1989 1990 dome emplacement like that in 1966 was on the margin of a north facing amphitheatre like summit crater the domes were confined on the east and west by steep cliffs of pre eruption cone building volcanic rocks and thus were constrained to grow vertically rapid upward growth in a precarious site caused each dome to spread preferentially to the north resulting in eventual gravitational collapse as long as the present conduit remains active at redoubt volcano any dome formed in a new eruption will be confined to a narrow steeply sloping gorge leading to rapid vertical growth and a tendency to collapse gravitationally repetitive cycles of dome formation and failure similar to those seen in 1989 1990 are probably the norm and must be considered in future hazard analyses of redoubt volcano

circulation and larval distribution in internal tidal bore warm fronts internal tidal bore warm fronts were observed during the summer of 1996 off the coast of southern california warm bore fronts had concentrating currents resulting from high frequency internal motions and from a larger two way flow the two way flow featured surface currents onshore and bottom currents offshore a sharp thermocline depression and high frequency large amplitude internal motions followed the leading edge of the bore with downwelling currents on the trailing side of the crest of the nonlinear internal waves and upwelling currents in front of the crest warm bores propagated onshore with a propagation speed c that ranged from 10 6 to 19 6 cm s 1 while time averaged frontal currents varied from 11 2 to 17 6 cm s 1 in the shallowest bin in one out of three cases c which implied that there were faster currents than the rate of advance of the front and which implied that the origin of surface frontal material is behind the front not in front of it three invertebrate larval taxa were found at all sites across fronts but only two intertidal barnacles pollicipes polymerus and chthamalus spp were concentrated at the front s surface while the subtidal bryozoan membranipora spp was not frontal pollicipes were more concentrated than were chthamalus the frontal downwelling currents observed suggested that concentrated larvae would have to swim upward in order to maintain depth pollicipes were abundant on the offshore warm side of the fronts but were absent or rare on the onshore colder side suggesting that the origin of frontal pollicipes was behind the front although an alternative cannot be ruled out conclusively chthamalus were more abundant at depth than at the surface at all sites except at the front where this pattern was reversed the origin of frontal chthamalus is uncertain membranipora were more abundant on the onshore colder side of the fronts and abundances were usually higher at depth than at surface lack of accumulation in this species may be due to its limited swimming capability

active mud volcanism observed with landsat 7 etm abstract mud volcanoes are relatively small spatter cones that erupt water laden mud and gases and occur throughout the world for many mud volcanoes the eruption of warm mud 10 40 c can be detected with high resolution thermal satellite imagery we demonstrate the utility of landsat 7 enhanced thematic mapper plus etm imagery for thermal monitoring of active mud volcanism we constrain the temperature and area of active mud discharge and estimate surface heat flux for two isolated mud volcanoes in the copper river basin alaska using band 6 10 4 12 5 m the heat flux results span a wide range due to uncertainties in the environmental conditions at the time of image acquisition but can be constrained to be less than 0 24 mw for each of the two mud volcanoes considering previously published field measurements with this higher resolution band 6 on the etm sensor as well as the high resolution thermal bands on the aster sensor reliable monitoring of mud volcanism on this scale is possible for the first time

aster observations of thermal anomalies preceding the april 2003 eruption of chikurachki volcano kurile islands russia abstract chikurachki volcano northern kurile islands chain paramushir island 50 20 n 155 27 e elevation 1816 m stratovolcano has been in a state of unrest for over twenty years its most recent eruption that began in april 2003 was preceded by an eruption between january and may 2002 thermal infrared images from the japanese united states advanced spaceborne thermal emission and reflection radiometer aster 5 tir channels 8 12 m 90 m pixel noise equivalent delta temperature ne t 0 1 0 3 k onboard the u s national aeronautics and space administration s terra polar orbiting spacecraft of a snow covered chikurachki volcano taken in january 2003 show muted evidence of thermal activity aster thermal infrared tir images from february 2003 however indicate warmer areas within the summit crater average whole pixel temperatures of adjacent summit slopes are in the range of 250 252 k while many summit crater whole pixel temperatures are 2 6 k greater a two component planck solution for the warmer pixels yields a solution of 275 277 k for 10 15 of the chikurachki summit crater and 285 295 k for 25 35 of a prominent hotspot on its flank an interpretation of this enhanced pre eruption heat flow is the presence of surface melt water the detection in aster data of such subtle precursory heat flow enhancement even retrospectively raises important issues for remote monitoring of dormant snow capped volcanoes especially those that threaten nearby populations like mt rainier

modeling reservoir heterogeneity within outer ramp carbonate facies using an outcrop analog san andres formation of the permian basin variably cyclic fusulinid rich outer ramp facies of the permian san andres formation are exposed along the algerita escarpment guadalupe mountains new mexico we have used the outcrop exposures and cored wells drilled adjacent to the outcrop to assess reservoir and interwell scale variability of permeability as a potential analog for carbonate reservoirs in the permian basin and elsewhere permeability distribution was evaluated using a field permeameter and conventional measurements on small core plugs taken along vertical and horizontal outcrop traverses and from the slim hole cores permeability is related to the variable development of depositional cycles within a small scale sequence and also to diagenetic overprinting geostatistical models of permeability variation honoring the geologic and petrophysical data were constructed and input into a waterflood simulator to understand the interactions between heterogeneity and flow variograms constructed from conventional plug analyses of permeability for a vertical outcrop transect contain a significant small scale signal noise as seen in the high nugget effect approximately 50 of the overall sample variance and have correlation ranges of less than 4 5 m 15 ft different vertical variogram characteristics are displayed by cyclic and less distinctly cyclic parts of the san andres variograms constructed for horizontal transect data from three distinct stratigraphic units have nearly identical properties overall the ranges of correlation are short 3 3 5 m 10 12 ft when compared to typical interwell distances supporting a nearly uncorrelated and highly variable permeability model using observed short ranges of vertical and horizontal correlation and honoring the vertical transect data cross sectional conditionally simulated permeability fields were generated and used in simulated waterfloods to investigate the sensitivities to an oil recovery model and overall fluid injection rate for this style of stratigraphy and cyclicity cyclic parts of the section are characterized by a potential for early water breakthrough and relatively high vertical sweep efficiencies within the less distinctly cyclic section waterflood fronts have a fingerlike profile and vertical sweep efficiency is generally poorer

volcano ice interactions precursory to the 2009 eruption of redoubt volcano alaska abstract in late summer of 2008 after nearly 20 years of quiescence redoubt volcano began to show signs of abnormal heat flow in its summit crater in the months that followed the excess heat triggered melting and ablation of redoubt s glaciers beginning at the summit and propagating to lower elevations as the unrest accelerated a variety of morphological changes were observed including the creation of ice cauldrons areas of wide spread subsidence punctures in the ice carved out by steam and deposition from debris flows in this paper we use visual observations satellite data and a high resolution digital elevation model of the volcanic edifice to calculate ice loss at redoubt as a function of time our aim is to establish from this time series a proxy for heat flow that can be compared to other data sets collected along the same time interval our study area consists of the drift glacier which flows from the summit crater down the volcano s north slope and makes up about one quarter of redoubt s total ice volume of 4 km 3 the upper part of the drift glacier covers the area of recent volcanism making this part of ice mass most susceptible to the effect of volcanic heating moreover melt water and other flows are channeled down the drift glacier drainage by topography leaving the remainder of redoubt s ice mantle relatively unaffected the rate of ice loss averaged around 0 1 m 3 s over the last four months of 2008 accelerated to over twenty times this value by february 2009 and peaked at greater than 22 m 3 s just prior to the first major explosion on march 22 2009 we estimate a cumulative ice loss over this period of about 35 million cubic meters m m 3

mineralogy early marine diagenesis and the chemistry of shallow water carbonate sediments abstract shallow water carbonate sediments constitute the bulk of sedimentary carbonates in the geologic record and are widely used archives of earth s chemical and climatic history one of the main limitations in interpreting the geochemistry of ancient carbonate sediments is the potential for post depositional diagenetic alteration in this study we use paired measurements of calcium 44ca 40ca or 44ca and magnesium 26mg 24mg or 26mg isotope ratios in sedimentary carbonates and associated pore fluids as a tool to understand the mineralogical and diagenetic history of neogene shallow water carbonate sediments from the bahamas and southwest australia we find that the ca and mg isotopic composition of bulk carbonate sediments at these sites exhibits systematic stratigraphic variability that is related to both mineralogy and early marine diagenesis the observed variability in bulk sediment ca isotopes is best explained by changes in the extent and style of early marine diagenesis from one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the fluid fluid buffered to one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the precursor sediment sediment buffered our results indicate that this process together with variations in carbonate mineralogy aragonite calcite and dolomite plays a fundamental and underappreciated role in determining the regional and global stratigraphic expressions of geochemical tracers 13c 18o major minor and trace elements in shallow water carbonate sediments in the geologic record our results also provide evidence that a large shallow water carbonate sink that is enriched in 44ca can explain the mismatch between the 44 40ca value of rivers and deep sea carbonate sediments and call into question the hypothesis that the 44 40ca value of seawater depends on the mineralogy of primary carbonate precipitations e g aragonite seas and calcite seas finally our results for sedimentary dolomites suggest that paired measurements of ca and mg isotopes may provide a unique geochemical fingerprint of mass transfer during dolomitization to better understand the paleo environmental information preserved in these enigmatic but widespread carbonate minerals

observation of a turbid plume using modis imagery the case of douro estuary portugal abstract the douro is one of the longest rivers in the iberian peninsula and represents the most important freshwater input into the atlantic ocean in the northwestern portuguese coast in order to fill the gaps on the comprehension of the spatial variability of the douro estuarine plume an innovative methodology was applied to observe and characterize this plume and its spatial and temporal variability using images of normalized water leaving radiance at 555 nm from modis moderate resolution imaging spectroradiometer in combination with long term concurrent wind tidal and river discharge data 2003 2011 this work evaluates the effect of the main drivers river discharge wind and tide on the plume features expected strong relationships between river discharge and turbid levels were detected a circular pattern is well distinct off douro estuary when the flow exceeds 500 m 3 s 1 under upwelling favorable winds and high river discharge regime an offshore expansion is observed during southerly winds there is a plume confinement to the coast easterly winds produce a bulge formation with an offshore detachment from the coast while westerly winds tend to confine freshwater close to the shoreline and decrease the cross shore advection under high river discharges a remarkable tidal influence in the near field regions is observed close to the coast and near the river mouth

characteristics of a surface buoyant jet tidal outflow from leschenault estuary in winter forms an unsteady surface buoyant jet in koombana bay on each outgoing tide as the water moves away from the exit channel and spreads radially over the bay it assumes a plumelike nature the mean features of this buoyant outflow such as the plume shape frontal celerity internal circulation and the bulk entrainment were measured in an intensive field program these features are shown to compare favorably with results from previous laboratory investigations and predictions from a simple inertia buoyancy force balance which includes entrainment at the front the stability of the plume frontal region was examined and it is shown that subfronts were present but their behavior cannot be explained by reference to previous work

forward modelling of carbonate platforms sedimentological and diagenetic constraints from an application to a flat topped greenhouse platform triassic southern alps italy abstract quantitative analysis of depositional systems using numerical models can provide insights into the interaction of sedimentological and diagenetic processes difficult to interpret from observation of the geological products alone numerical models can highlight the interactions between controlling parameters and generate best estimate simulations of case studies from the geological record different data sources e g outcrop data uniformitarian constraints paleogeography need to be considered in the process of defining the parameters required to produce models that honour individual case studies we present a best estimate forward model of a high relief triassic carbonate platform southern alps italy generated using carb3d a 3d process based forward modelling package able to simulate sedimentary facies geometries and early diagenesis of isolated carbonate platforms the parameters used for the presented forward model have been deduced by the study of architectural sedimentological and diagenetic features of the platform and by data from modern and ancient analogues sensitivity analysis is used to tune values of the parameters within ranges defined from field laboratory and uniformitarian constraints critical evaluation of the model allowed 1 verification of the validity of the used parameters 2 evaluation of the interaction between controlling parameters 3 development of a numerical model that can be used for quantitative elaborations furthermore the process of generating the numerical model required a detailed interpretation of field and laboratory data crucial to define the required input parameters modelling the studied carbonate platform also enabled evaluation of the effects of the interaction between productivity environmental energy and creation of accommodation space promoting the understanding of their role on the architecture of carbonate systems forward modelling also allows the integration of data from conventional data sets with data from present day observations and seismic geometries promoting a transition from a qualitative to a semi quantitative quantitative sedimentological approach forward models can further be used to parameterise petrophysical properties of complex geobodies with potential application for the management of georesources

photogrammetric monitoring of lava dome growth during the 2009 eruption of redoubt volcano abstract the 2009 eruption of redoubt volcano alaska began with a phreatic explosion on 15 march followed by a series of at least 19 explosive events and growth and destruction of at least two and likely three lava domes between 22 march and 4 april on 4 april explosive activity gave way to continuous lava effusion within the summit crater we present an analysis of post 4 april lava dome growth using an oblique photogrammetry approach that provides a safe rapid and accurate means of measuring dome growth photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed wing volcanic gas surveys produced a series of digital elevation models dems of the lava dome from 16 april to 23 september the dems were used to calculate estimates of volume and time averaged extrusion rates and to quantify morphological changes during dome growth effusion rates ranged from a maximum of 35 m 3 s 1 during the initial two weeks to a low of 2 2 m 3 s 1 in early summer 2009 the average effusion rate from april to july was 9 5 m 3 s 1 early rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater in mid to late april the volume of the dome had reached 36 10 6 m 3 roughly half of the total volume and dome growth within the summit crater began to be limited by confining crater walls to the south east and west once the dome reached the steep north sloping gorge that breaches the crater growth decreased to the south but the dome continued to inflate and extend northward down the gorge effusion slowed during 16 april 1 may but in early may the rate increased again this rate increase was accompanied by a transition to exogenous dome growth from mid may to july the effusion rate consistently declined the decrease is consistent with observations of reduced seismicity gas emission and thermal anomalies as well as declining rates of geodetic deflation or inflation these trends suggest dome growth ceased by july 2009 the volume of the dome at the end of the 2009 eruption was about 72 10 6 m 3 more than twice the estimated volume of the largest dome extruded during the 1989 1990 eruption in total the 2009 dome extends over 400 m down the glacial gorge on the north end of the crater with a total length of 1 km width of 500 m and an average thickness of 200 m

using satellite data to characterize the temporal thermal behavior of an active volcano mount st helens wa 1 aster thermal infrared data over mt st helens were used to characterize its thermal behavior from jun 2000 to feb 2006 prior to the oct 2004 eruption the average crater temperature varied seasonally between 12 and 6 c after the eruption maximum single pixel temperature increased from 10 c oct 2004 to 96 c aug 2005 then showed a decrease to feb 2006 the initial increase in temperature was correlated with dome morphology and growth rate and the subsequent decrease was interpreted to relate to both seasonal trends and a decreased growth rate increased cooling rate possibly suggesting a significant change in the volcanic system a single pixel aster thermal anomaly first appeared on oct 1 2004 eleven hours after the first eruption 10 days before new lava was exposed at the surface by contrast an automated algorithm for detecting thermal anomalies in modis data did not trigger an alert until dec 18 however a single pixel thermal anomaly first appeared in modis channel 23 4 um on oct 13 12 days after the first eruption 2 days after lava was exposed the earlier thermal anomaly detected with aster data is attributed to the higher spatial resolution 90 m compared with modis 1 km and the earlier visual observation of anomalous pixels compared to the automated detection method suggests that local spatial statistics and background radiance data could improve automated detection methods

the 1989 1990 eruptions of redoubt volcano an introduction abstract redoubt volcano located on the west side of cook inlet in south central alaska erupted explosively on over 20 separate occasions between december 14 1989 and april 21 1990 fourteen lava domes were emplaced in the summit area thirteen of which were subsequently destroyed the eruption caused economic losses estimated at over 160 000 000 making this the second most costly eruption in u s history this economic impact provided the impetus for a integrated comprehensive account of an erupting volcano using both modern and classical research and modern techniques which in turn led to advances in eruption monitoring and interpretation research on such topics as dome formation and collapse and the resulting pyroclastic flows elutriated ash lightning tephra and flooding was blended with the rapid communication of associated hazards to a large user group the seismology successes in predicting and monitoring eruption dynamics were due in part to 1 the recognition of long period seismic events as indicators of the readiness of the volcano to erupt and 2 to the development of new tools that allowed the seismicity to be assessed instantaneously integrated studies of the petrology of erupted products and volatile content over time gave clues as to the progress of the eruption towards completion

investigating crater lake warming using aster thermal imagery case studies at ruapehu poas kawah ijen and copahue volcanoes abstract a two channel or split window algorithm designed to correct for atmospheric conditions was applied to thermal images taken by the advanced spaceborne thermal emission and reflection radiometer aster of lake yugama on kusatsu shirane volcano in japan in order to measure the temperature of its crater lake these temperature calculations were validated using lake water temperatures that were collected on the ground overall the agreement between the temperatures calculated using the split window method and ground truth is quite good typically 1 5 c for cloud free images data from fieldwork undertaken in the summer of 2004 at kusatsu shirane allow a comparison of ground truth data with the radiant temperatures measured using aster imagery further images were analyzed of ruapehu poas kawah ijen and copahue volcanoes to acquire time series of lake temperatures a total of 64 images of these 4 volcanoes covering a wide range of geographical locations and climates were analyzed results of the split window algorithm applied to aster images are reliable for monitoring thermal changes in active volcanic lakes these temperature data when considered in conjunction with traditional volcano monitoring techniques lead to a better understanding of whether and how thermal changes in crater lakes aid in eruption forecasting

voluminous ice rich and water rich lahars generated during the 2009 eruption of redoubt volcano alaska abstract redoubt volcano in south central alaska began erupting on march 15 2009 and by april 4 2009 had produced at least 20 explosive events that generated multiple plumes of ash and numerous lahars the 3108 m high snow and ice clad stratovolcano has an ice filled summit crater that is breached to the north the volcano supports about 4 km 3 of ice and snow and about 1 km 3 of this makes up the drift glacier on the north side of the volcano explosive eruptions between march 23 and april 4 which included the destruction of at least two lava domes triggered significant lahars in the drift river valley on march 23 and april 4 and several smaller lahars between march 24 and march 31 mud line high water marks character of deposits areas of inundation and estimates of flow velocity revealed that the lahars on march 23 and april 4 were the largest of the eruption in the 2 km wide upper drift river valley average flow depths were at least 2 5 m average peak flow velocities were likely between 10 and 15 ms 1 and peak discharges were on the order of 10 4 10 5 m 3 s 1 the area inundated by lahars on march 23 was at least 100 km 2 and on april 4 about 125 km 2 two substantial lahars emplaced on march 23 and one on april 4 had volumes on the order of 10 7 10 8 m 3 and were similar in size to the largest lahar of the 1989 90 eruption the two principal march 23 lahars were primarily flowing slurries of snow and ice derived from drift glacier and the drift river valley where seasonal snow and tabular blocks of river ice were entrained and incorporated into the lahars despite morphologic evidence of two lahars only a single deposit up to 5 m thick was found in most places and it contained about 80 95 of poorly sorted massive to imbricate assemblages of snow and ice clasts the deposit was frozen soon after it was emplaced and later eroded and buried by the april 4 lahar the lahar of april 4 in contrast was primarily a hyperconcentrated flow as interpreted from 1 to 6 m thick deposits of massive to horizontally stratified sand to fine gravel rock material in the april 4 lahar deposit is predominantly juvenile andesite whereas rock material in the march 23 deposit is rare and not obviously juvenile we infer that the lahars generated on march 23 were initiated by a rapid succession of vent clearing explosions that blasted through about 50 100 m of crater filling glacier ice and snow producing a voluminous release of meltwater from drift glacier the resulting surge of water entrained snow fragments of glacier and river ice and river water along its flow path small volume pyroclastic flows possibly associated with destruction of a small dome or minor eruption column collapses may have contributed additional meltwater to the march 23 lahars meltwater generated by subglacial hydrothermal activity and stored beneath drift glacier may have been ejected or released rapidly as well the april 4 lahar was initiated when hot dome collapse pyroclastic flows entrained and swiftly melted snow and ice on drift glacier the resulting meltwater incorporated pyroclastic debris and rock material from drift glacier to form the largest lahar of the 2009 eruption the peak discharge of the april 4 lahar was in the range of 60 000 160 000 m 3 s 1 for comparison the largest lahar of the 1989 90 eruption had a peak discharge of about 80 000 m 3 s 1 lahars generated by the 2009 eruption led to significant channel aggradation in the lower drift river valley and caused extensive inundation at an oil storage and transfer facility located there the april 4 2009 lahar was 6 30 times larger than the largest meteorological floods known or estimated in the drift river drainage

evaluation of redoubt volcano s sulfur dioxide emissions by the ozone monitoring instrument abstract the 2009 eruption of redoubt volcano alaska provided a rare opportunity to compare satellite measurements of sulfur dioxide so2 by the ozone monitoring instrument omi with airborne so2 measurements by the alaska volcano observatory avo herein we 1 compare omi and airborne so2 column density values for redoubt s tropospheric plume 2 calculate daily so2 masses from mount redoubt for the first three months of the eruption 3 develop simple methods to convert daily measured so2 masses into emission rates to allow satellite data to be directly integrated with the airborne so2 emissions dataset 4 calculate cumulative so2 emissions from the eruption and 5 evaluate omi as a monitoring tool for high latitude degassing volcanoes a linear correlation r2 0 75 is observed between omi and airborne so2 column densities omi daily so2 masses for the sample period ranged from 60 1 kt on 24 march to below detection limit with an average daily so2 mass of 6 7 kt the highest so2 emissions were observed during the initial part of the explosive phase and the emissions exhibited an overall decreasing trend with time omi so2 emission rates were derived using three methods and compared to airborne measurements this comparison yields a linear correlation r2 0 82 with omi derived emission rates consistently lower than airborne measurements the comparison results suggest that omi s detection limit for high latitude springtime conditions varies from 2000 to 4000 t d cumulative so2 masses calculated from daily omi data for the sample period are estimated to range from 542 to 615 kt with approximately half of this so2 produced during the explosive phase of the eruption these cumulative masses are similar in magnitude to those estimated for the 1989 90 redoubt eruption strong correlations between daily omi so2 mass and both tephra mass and acoustic energy during the explosive phase of the eruption suggest that omi data may be used to infer relative eruption size and explosivity further when used in conjunction with complementary datasets omi daily so2 masses may be used to help distinguish explosive from effusive activity and identify changes in lava extrusion rates the results of this study suggest that omi is a useful volcano monitoring tool to complement airborne measurements capture explosive so2 emissions and provide high temporal resolution so2 emissions data that can be used with interdisciplinary datasets to illuminate volcanic processes

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

a comparison of field and satellite derived thermal flux at piton de la fournaise implications for the calculation of lava discharge rate we present thermal measurements made by high spatial resolution ground based a hand held thermal camera and low spatial resolution space based modis instruments for a lava flow field active during the last phase of the may july 2003 eruption at piton de la fournaise la reunion multiple oblique ground based thermal images were merged to provide full coverage of the flow field these were then corrected for path length attenuation and orthorectified allowing the at surface radiance emitted by the flow field to be estimated comparison with the radiance recorded by the modis sensors during the eruption reveals that for clear sky conditions and moderate to low viewing angles satellite zenith 40 the satellite measurements represent 90 of the at surface radiance and thus represent valuable data for quantifying volcanic thermal anomalies nevertheless extreme viewing geometries and the presence of clouds strongly affect the radiance reaching the sensor and affected data from 94 of the overpasses ground based thermal data were used to investigate an empirical relationship between the radiant heat flux and lava discharge rate during the emplacement of pahoehoe flows while the average radiation temperature for flow surface that were 6 24 h old ranged between 500 k and 625 k the ratio between radiative heat flux and time averaged lava discharge rate tadr ranged between 1 5 108 j m 3 and 3 5 108 j m 3 this relationship was used to estimate tadr values from optimal modis data and produced results in line with those obtained from gps surveys coppola et al 2005 our results underscore the importance of ground based thermal analysis for the interpretation of satellite measurements particularly in terms of calculating discharge rate trends

mixing of a dye tracer in the delaware plume comparison of observations and simulations 1 in april 2003 we injected rhodamine wt fluorescent dye into the halocline at the base of the delaware river plume during an upwelling event the dye immediately bifurcated one third of the dye moved offshore with a portion of the plume while the other 2 3 remained within the halocline near the coastline this behavior has not been previously observed and it presents a strong challenge to contemporary coastal ocean models here we employ a numerical model of delaware bay and the adjacent coastal region that incorporates the mellor yamada level 2 5 turbulence closure scheme to simulate the observed dye injection event comparison between the simulation and observations reveals that the model is able to successfully reproduce the flow field simulating the separation and subsequent advection of the dye consequently the simulation is used to examine the relative effects of wind and buoyancy driven transport on mixing and advection of the dye comparison of simulated and observed plumes reveals that the model accurately reproduces the observed mixing and accompanying vertical salt flux within the offshore plume examination of the simulation reveals a unique combination of wind and buoyancy driven flow that results in the dye remaining in the halocline of the onshore plume despite significant vertical mixing due to winds the strong stratification within the inshore plume causes the closure scheme to shut off the vertical diffusivities leaving the circulation model with arbitrarily chosen constant background values varying these values reveals only a weak dependence of the salt flux within the highly stratified regions due to the highly localized nature of the salt flux

subtidal flow structure at the turning region of a wide outflow plume 1 a series of underway current velocity profiles and near surface temperature and salinity measurements were combined with temperature and salinity profiles to characterize the subtidal flow structure at the turning region of a wide plume the chesapeake bay outflow plume in this context wide refers to the ratio of lateral plume expansion to internal radius of deformation being greater than one observations were obtained in september and november of 1996 and in february and may of 1997 with the idea of capturing the variability in forcing conditions typically associated with these seasons however regional precipitation patterns yielded similar buoyancy forcing conditions for the four surveys and among the wettest years on record this buoyancy forcing produced a well delineated outflow plume that separated from the coast on its way out the estuary the plume separation acted in conjunction with frictional effects to delineate an inshore front in addition to the customarily described offshore front the outflow plume was markedly constrained by the chesapeake channel which was also the main conduit of shelf waters toward the estuary the bathymetric influence was also evident in the surface salinity field the mean flows and the volume fluxes the offshore extent of the plume was found between the scale predicted by geostrophic dynamics internal rossby radius and that predicted by cyclostrophic dynamics such offshore extent was most likely linked to the plume interactions with the bathymetrically steered up estuary flow this was corroborated by an analytical solution that explored the dynamical balance among pressure gradient coriolis accelerations and friction in addition to being influenced by bathymetry the chesapeake bay outflow plume was modified by local and remote effects related to atmospheric forcing

the aster spectral library version 2 0 abstract the advanced spaceborne thermal emission reflection radiometer aster on nasa s terra platform has been widely used in geological and other science studies in support of aster studies a library of natural and man made materials was compiled as the aster spectral library v1 2 and made available from http speclib jpl nasa gov the library is a collection of contributions in a standard format with ancillary data from the jet propulsion laboratory jpl johns hopkins university jhu and the united states geological survey usgs a new version of the library v2 0 is now available online or via cd which includes major additions to the mineral and rock spectra the aster library provides a comprehensive collection of over 2300 spectra of a wide variety of materials covering the wavelength range 0 4 15 4 m

a description of tides near the chesapeake bay entrance using in situ data with an adjoint model 1 time series of surface elevation and current velocity in the vicinity of the chesapeake bay entrance are assimilated into a linear barotropic model using an iterative adjoint method tide surface elevations noaa nos tidal data moored acoustic doppler current profiler adcp and ocean surface current radar oscr data are included in the assimilation data are analyzed for three tidal constituents m2 s2 o1 tidal series are constructed from these constituents and then used in the model assimilations statistics of predicted currents compare favorably with those calculated from data not used in the assimilation an error analysis of the data distribution is performed for the m2 tidal component showing lower errors near assimilation data series but large errors particularly for velocity at some locations addition of a hypothetical current mooring dramatically reduces errors over most of the domain we believe these results give the most demonstrably accurate description now available of tidal currents for this region of strong currents and heavy shipping

impact of upscaling on solute transport traveltimes scale dependence of dispersivity and propagation of uncertainty 1 efficiency constraints in applying numerical models to real problems force the use of a coarse discretization of the domain compared with the detailed scale required for the most adequate description of the system upscaling encompasses the methods that transfer small scale information to the computational scale the loss of small scale information by upscaling aquifer properties to construct a numerical model largely modifies the true heterogeneous structure of the aquifer compromising the final predictions of solute transport we present extensive monte carlo solute transport simulations in heterogeneous porous media to investigate 1 the impact of upscaling on the evolution of solute plumes and 2 the propagation of uncertainty through upscaling in doing this we analyze the benefits of using enhanced block dispersion tensors in the advection dispersion equation to compensate for the loss of information it is shown that upscaling does not affect the median traveltimes of particles reaching a control location but the tail of breakthrough curves is largely underestimated it is also observed that normal upscaled transport models can largely underestimate the spreading of solute plumes even if block dispersivities are calculated as being representative of within block heterogeneity discrepancies are mainly attributed to the mass transfer interaction between grid blocks of the numerical model and the use of a simplistic representation of the block hydraulic conductivity tensor using the small perturbation stochastic approach we found that mass transfer effects are still significant even for block sizes of the numerical model greater than 30 correlation scales moreover upscaling is shown to have a substantial impact on the uncertainty predicted by solute transport models which is not compensated by the use of enhanced block dispersion tensors for very heterogeneous media simulation results showed the inability of the classical advection dispersion equation to simultaneously reproduce the tail of the breakthrough curve and its uncertainty in the upscaled model in those cases results indicated that either a mass transfer model allowing solute mass exchange between high and low conductivity zones encountered within a grid block of the numerical model or the continuous time random walk model expressing the retardation of solute particles passing through low conductivity regions inside a grid block by means of a transition time distribution function might suppose a better upscaled transport model

circulation mixing and exchange processes in the vicinity of tidal inlets a numerical study the circulation in the vicinity of an idealized tidal inlet connecting a continental shelf and a coastal sound is examined the circulation is forced by an m2 tide and a weakly buoyant discharge the buoyant discharge forms a plume in the coastal ocean and induces a distinct anticyclonic circulation at the plume edge that is maintained throughout the tidal cycle we focus on the plume s onset and its evolution over 5 10 tidal cycles over the timescales considered the plume was roughly circular slightly skewed in the along coast direction the model solution yielded high vertical ekman numbers e o 5 in the vicinity of the inlet mouth decreasing seaward from the inlet to an order of magnitude smaller e 0 25 at the seaward edge of the plume passive particles released in the region seaward of the inlet mouth were used to describe the exchange between the coastal region and the inlet a marked asymmetry between ebb and flood flows is observed in the vicinity of the inlet with jet like ebbing currents and weaker potential flow like flooding currents over a tidal cycle net exchanges between the coastal ocean and the inlet are found to be spatially and temporally dependent that is particle trajectories depend on the release point and the time of the release in the tidal cycle the near inlet residual circulation shows significant differences in the absence of stratification

early dolomitization in the lower cretaceous shallow water carbonates of southern apennines italy clues about palaeoclimatic fluctuations in western tethys abstract a multidisciplinary study of the dolomitized bodies present in the lower cretaceous platform carbonates of mt faito southern apennines italy was carried out in order to explore the connection between early dolomite formation and fluctuating climate conditions the berriasian aptian investigated succession is 466 m thick and mainly consists of shallow water lagoonal limestones with frequent dolomite caps the dolomitization intensity varies along the succession and reaches its peak in the upper hauterivian lower barremian interval where it is present a completely dolomitized interval about 100 m thick field relations petrography mineralogy and geochemistry of the analyzed dolomite bodies allowed identifying two populations of early dolomites a fine medium crystalline fmdol and a coarse crystalline dolomite cdol both interpreted as the product of mesohaline water reflux according to our interpretation fmdol precipitated from concentrated brines in the very early stage of the reflux process producing typical sedimentary features as dolomite caps in the successive step of the process the basin ward latent reflux precipitated cdol from less concentrated brines a peculiar feature of the studied succession is the great consistency between stratigraphic distribution of dolomite bodies and their geochemical signature the completely dolomitized hauterivian barremian interval in fact is characterized by geochemical values suggesting an origin from distinctly saltier brines considering that the observed near surface dolomitization process is controlled by physical and chemical parameters reflecting the paleoenvironmental and paleoclimatic conditions during dolomite formation we propose that the stratigraphically controlled dolomitization intensity reflects periodic fluctuations in the salinity of dolomitizing fluid in turn controlled by long term climate oscillations the present work highlights that the stratigraphic distribution of early diagenetic dolomite may be used as proxy to define the climatic fluctuations that have influenced the sedimentary dynamics in the early cretaceous moreover considering that a comparable early dolomite distribution is present also in the dinaric platform we suggest that a regional scale climate control acted on early dolomite formation and distribution refining the knowledge of such a key control may have a significative impact on hydrocarbon reservoir characterization and exploration in the periadriatic area

calculation of lava effusion rates from landsat tm data we present a thermal model to calculate the total thermal flux for lava flowing in tubes on the surface or under shallow water once defined we use the total thermal flux to estimate effusion rates for active flows at kilauea hawaii on two dates input parameters were derived from landsat thematic mapper tm field and laboratory measurements using these parameters we obtain effusion rates of 1 76 0 57 and 0 78 0 27 m3 s 1 on 23 july and 11 october 1991 respectively these rates are corroborated by field measurements of 1 36 0 14 and 0 89 0 09 m3 s 1 for the same dates kauahikaua et al 1996 using weather satellite avhrr data of lower spatial resolution we obtain similar effusion rates for an additional 26 dates between the two tm derived measurements we assume that although total effusion rates at the source declined over the period the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable such synergetic use of remotely sensed data provides measurements that can a contribute to monitoring flow field evolution and b provide reliable numerical data for input into rheological and thermal models we look forward to being able to produce estimates for effusion rates using data from high spatial resolution sensors in the earth observing system eos era such as landsat 7 the hyperspectral imager the advanced spaceborne thermal emission spectrometer and the advanced land imager

guadalupe mountains west texas and new mexico key excursions the carbonate and siliciclastic outcrops of the guadalupe mountains in the permian basin of west texas and new mexico have provided a rich set of basic and advanced conceptual models for geologists across the entire spectrum of experience for carbonate ramp and steep rimmed platform settings as well as the adjacent deep water siliciclastics not dealt with here fundamental questions regarding the scale and continuity of reservoir pay facies the depositional patterns and profiles of shelf to slope clinoforms the width of facies tracts on ramps and rimmed platforms the distribution and internal composition of reef complexes the link between reef development and slope depositional patterns styles of early and late diagenesis including dolomitization and karstification and structural patterns can all be addressed in the guadalupe mountains exposures

dolomite and dolomitization of the permian khuff c reservoir in ghawar field saudi arabia abstract the permian khuff c reservoir in saudi arabia is known for its lateral and vertical heterogeneity caused mainly by dolomitization detailed petrographic analysis of 600 thin sections from six cored wells revealed three main replacive dolomite fabrics 1 fabric preserving mimetic fpm 2 fabric preserving nonmimetic fpnm and 3 fabric destructive fd dolomites crystal sizes are mostly less than or equal to 20 m for fpm dolomite less than or equal to 50 m for fpnm dolomite and less than or equal to 100 m for fd dolomite the fpm dolomite decreases in abundance and fpnm dolomite increases in abundance with increasing grain content of the facies the 18 o values of dolostones although considered an obsolete term dolostone is used here to mean rock containing 80 dolomite indicate early dolomitization at low temperatures in permian seawater or evaporated seawater with landward facies mudstone and wackestone generally dolomitized by more evaporated waters and seaward grainy facies generally dolomitized by less evaporated more normal marine seawaters stratigraphic variations in the dolostones 18 o values track with facies variations through fourth order depositional sequences and indicate that different stratigraphic bodies of dolomite formed from seawaters with different degrees of evaporation the 13 c values of the dolostones exhibit temporal trends inherited from the precursor limestones variations in the lateral and vertical abundance of dolomite and dolomite fabrics in the propensity for each facies to be dolomitized and in the dolomites oxygen isotopic values all suggest that multiple dolomitization events occurred in the khuff c reservoir as depositional cycles accumulated with some dolostones overprinted by younger events average porosities of grain rich dolostones are greater than those of mud rich dolostones indicating that depositional facies preordained porosity distribution within the dolostones however the more evaporated the dolomitizing fluid the more likely dolomitization resulted in lower porosity regardless of facies

numerical analysis of seawater circulation in carbonate platforms ii the dynamic interaction between geothermal and brine reflux circulation density driven seawater circulation may occur in carbonate platforms due to geothermal heating and or reflux of water of elevated salinity in geothermal circulation lateral contrasts in temperature between seawater and platform groundwa ters warmed by the geothermal heat flux result in upward convective flow with colder seawater drawn into the platform at depth with reflux circulation platform top waters concentrated by evaporation flow downward displacing less dense underlying ground waters we have used a variable density groundwater flow model to examine the pattern magnitude and interaction of these two different circulation mechanisms for mesosaline platform top waters 50 and brines concentrated up to saturation with respect to gypsum 150 and halite 246 geothermal circulation most active around the platform margin becomes restricted and eventually shut off by reflux of brines from the platform interior towards the margin the persistence of geothermal circulation is dependent on the rate of brine reflux which is proportional to the concentration of platform top brines and also critically dependent on the magnitude and distribution of permeability low permeability evaporites can severely restrict reflux whereas high permeability units in hydraulic continuity enhance brine transport reduction in permeability with depth and anisotropy of permeability kv kh focuses flow laterally in the shallow subsurface 1 km resulting in a horizontally elongated brine plume aquifer porosity and dispersivity are relatively minor controls on reflux platform brines can entrain surficial seawater when brine generating conditions cease but the platform top remains submerged a variant of reflux we term latent reflux brines concentrated up to gypsum saturation have relatively long residence times of at least 100 times the duration of the reflux event they thus represent a long term control on post reflux groundwater circulation and conse quently on the rates and spatial patterns of shallow burial diagenesis such as dolomiti zation

high resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at redoubt volcano alaska abstract a combination of satellite and airborne high resolution visible and thermal infrared tir image data detected and measured changes at redoubt volcano during the 2008 2009 unrest and eruption the tir sensors detected persistent elevated temperatures at summit ice melt holes as seismicity and gas emissions increased in late 2008 to march 2009 a phreatic explosion on 15 march was followed by more than 19 magmatic explosive events from 23 march to 4 april that produced high altitude ash clouds and large lahars two or three lava domes extruded and were destroyed between 23 march and 4 april after 4 april the eruption extruded a large lava dome that continued to grow until at least early july 2009

the geologic history of redoubt volcano alaska abstract redoubt volcano is a composite cone built on continental crust at the northeast end of the aleutian arc magmas erupted at redoubt are medium k calc alkaline basalts andesites and dacites the eruptive history of the volcano can be divided into four parts the early explosive stage early cone building stage late cone building stage and post glacial stage the most silicic products of the volcano were erupted during the early explosive stage about 0 888 ma and include pumiceous pyroclastic flow deposits block and ash flow deposits and a dome or shallow intrusive complex basalt and basaltic andesite lava flows and scoria and ash flows were produced during the early cone building stage which was underway by 0 340 ma during the late cone building stage andesitic lava flows and block and ash flows were emplaced airfall deposits produced during post glacial eruptions are silicic andesite in composition since the early cone building stage magmas have become progressively more silicic but none are as silicic as those in the early explosive stage limited pb and sr isotopic data suggest that redoubt magmas were contaminated by north american continental crust

doppler weather radar observations of the 2009 eruption of redoubt volcano alaska abstract the u s geological survey usgs deployed a transportable doppler c band radar during the precursory stage of the 2009 eruption of redoubt volcano alaska that provided valuable information during subsequent explosive events we describe the capabilities of this new monitoring tool and present data captured during the redoubt eruption the minimax 250 c mm 250c radar detected seventeen of the nineteen largest explosive events between march 23 and april 4 2009 sixteen of these events reached the stratosphere above 10 km within 2 5 min of explosion onset high column and proximal cloud reflectivity values 50 to 60 dbz were observed from many of these events and were likely due to the formation of mm sized accretionary tephra ice pellets reflectivity data suggest that these pellets formed within the first few minutes of explosion onset rapid sedimentation of the mm sized pellets was observed as a decrease in maximum detection cloud height the volcanic cloud from the april 4 explosive event showed lower reflectivity values due to finer particle sizes related to dome collapse and related pyroclastic flows and lack of significant pellet formation eruption durations determined by the radar were within a factor of two compared to seismic and pressure sensor derived estimates and were not well correlated ash dispersion observed by the radar was primarily in the upper troposphere below 10 km but satellite observations indicate the presence of volcanogenic clouds in the stratosphere this study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions

exploring the limits of identifying sub pixel thermal features using aster tir data abstract understanding the characteristics of volcanic thermal emissions and how they change with time is important for forecasting and monitoring volcanic activity and potential hazards satellite instruments view volcanic thermal features across the globe at various temporal and spatial resolutions thermal features that may be a precursor to a major eruption or indicative of important changes in an on going eruption can be subtle making them challenging to reliably identify with satellite instruments the goal of this study was to explore the limits of the types and magnitudes of thermal anomalies that could be detected using satellite thermal infrared tir data specifically the characterization of sub pixel thermal features with a wide range of temperatures is considered using aster multispectral tir data first theoretical calculations were made to define a thermal mixing detection threshold for aster which quantifies the limits of aster s ability to resolve sub pixel thermal mixing over a range of hot target temperatures and pixel areas then aster tir data were used to model sub pixel thermal features at the yellowstone national park geothermal area hot spring pools with temperatures from 40 to 90 c and at mount erebus volcano antarctica an active lava lake with temperatures from 200 to 800 c finally various sources of uncertainty in sub pixel thermal calculations were quantified for these empirical measurements including pixel resampling atmospheric correction and background temperature and emissivity assumptions

outcrop constrained hydrogeological simulations of brine reflux and early dolomitization of the permian san andres formation our hydrogeologic model tests the effectiveness of brine reflux as the mechanism for early dolomitization of the permian san andres formation brine circulation is constrained by sequence stratigraphic parameters and a heterogeneous distribution of petrophysical properties based on outcrop data the model simulates accumulation of the san andres platform and calculates fluid flow and solute transport in response to relative sea level fluctuations it tracks porosity loss caused by compaction and the concomitant permeability feedback the amount of dolomite potentially formed is calculated by means of a magnesium mass balance between brine and rock results show that 1 brine reflux is an effective mechanism to deliver magnesium to dolomitize large carbonate successions 2 relative sea level controlled transient boundary conditions result in intricate flow and salinity patterns that can generate irregular dolomite bodies with complex spatial distributions 3 pervasive dolomitization can result from several short lived reflux events by the amalgamation of brine plumes sourced in different locations and times and 4 the model successfully recreates the dolostone and limestone patterns observed in san andres outcrops

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

numerical modeling of reflux dolomitization in the grosmont platform complex upper devonian western canada sedimentary basin the upper devonian grosmont platform in the western canada sedimentary basin is a pervasively dolomitized giant heavy oil reservoir with reserves of 317 billion bbl of bitumen the principal type of grosmont platform dolomite formed early and on the basis of stratigraphic and geochemical evidence is interpreted as early diagenetic reflux dolomite we use a numerical ground water flow model to investigate the viability of reflux to dolomitize the grosmont platform we simulate reflux at four key stages of platform evolution incorporating the transient effects of changes in platform architecture rock properties and the salinity of platform top waters the pattern and magnitude of reflux is critically controlled by permeability and the distribution of platform top brines which are concentrated up to gypsum saturation reflux flow is focused in the relatively permeable carbonates of the grosmont formation and is from the platform interior toward the platform margin the 120 m thick shales of the ireton formation that separate the grosmont and cooking lake formations restrict cross formational flow and brine transport during a 100 k y period of relative sea level rise and platform top drowning brines of reflux origin continue to sink and entrain platform top waters latent reflux where the intervening aquitards are thin or absent reefs of the leduc formation capture reflux brines from the overlying grosmont platform and focus cross formational brine transport lateral contrasts in salinity are sufficient to drive a series of free convection cells in the relatively permeable reefs of the leduc formation computed distributions of fluid flux in conjunction with magnesium mass balance calculations that incorporate the range of uncertainty particularly in permeability support the suggestion that the reflux of gypsum saturated brines could have formed much if not most of the dolomite in the grosmont formation in the 1 6 m y available

differences in landsat tm derived lava flow thermal structures during summit and flank eruption at mount etna abstract the simultaneous solution of the planck equation the so called dual band technique for two shortwave infrared landsat thematic mapper tm bands allows an estimate of the fractional area of the hottest part of an active flow and the temperature of the cooler crust here the dual band method has been applied to a time series of mount etna eruptions the frequency distribution of the fractional area of the hottest component reveals specific differences between summit and flank lava flows the shape of the density function shows a trend consistent with a gaussian distribution and suggests a relationship between the moments of the distribution and the emplacement environment because flow composition of etnean lavas generally remains constant during the duration of their emplacement it appears that the shape of any particular frequency distribution is probably related to fluid mechanical aspects of flow emplacement that affect flow velocity and flow heat loss and thus the rate of formation of the surface crust these factors include the influence of topographical features such as changes in slope gradient changes in volume effusion rate and progressive downflow increases in bulk or effective viscosity a form of the general theoretical solution for the dual band system which illustrates the relationship between radiance in tm bands 5 and 7 corresponding to hot fractional area and crust temperature is presented generally speaking it appears that for a given flow at any point in time larger fractional areas of exposed hot material are correlated with higher temperatures and that while the overall shape of that distribution is common for the flows studied its amplitude and slope reflect individual flow rheological regimes